1 Lucky Texan

I wonder what a system would feel like if there were air in the ABS pump? how is that system bled?

a 98 in Indiana could have rusted lines - any loss of fluid or drips from the gas tank area?

one option, you might find an entire trans out of a wreck (LKQ or car-part.com) ,maybe with less miles.

there's a way to measure the tires with some chalk and a run on some pavement, but maybe you can get a new tire to match the other 3 new ones you're picking up? some people have found a single, slightly worn tire on ebay or craigslist to match a partial set after a sidewall blow-out. (will FRS rims fit on your car? same bolt pattern?)

Subaru has recommended for decades that tires be within 1/4" of each other in rolling circumference. Reality seems to indicate the system may not be quite as sensitive as they want you to guard against but, any tire (axle actually) turning faster than the others could be sensed as slippage and cause the AWD system to begin engaging. the fact that there are different tires on the car may also point to prior abuse of the system by mixing tires.

hmmm, the different brands 'could' be contributing to the issue... as an experiment, put the same brands of the tires you have on each SIDE (or opposite corners) and see if there is any improvement.

Impreza is a lighter car, but, maybe the tires are over-inflated? Did you buy it used? maybe the prev. owner modified the suspension?

maybe ask/dig around at NASIOC and subaruoutback Forums.

did the car have normal feeling brakes in the past? any work done or wrecks before the problem began? inspect all the brake calipers and caliper brackets. are all the brake pads wearing evenly? any wedge-shaped? brake lines bled of air? any damage or major rust around the firewall where the MC is mounted? after idling the car, pull the hose off the booster, there should be a woosh of air go into it. If not, it could have a leak? (I don't guess it's possible the booster hose is on backwards? maybe test by blowing into it - should block blowing from the engine side)

just to be clear, all 4 tires are exactly the same? brand/model/size? did the po swap any parts? rear diff or transmission?

guess there isn't a CD stuck in it.

did you use the 'line' indented on one of the 'tabs' at the rear of the crank sprocket? Or, did you use the 'triangle' (some call it an arrow) at the front of the crank sprocket? (you MUST use the line. and none of those tabs can be broken off) the 'tooth count' referred to is the number of teeth between the various pulley index marks. Not a bad idea to use the wrench to turn the system trough 2 revolutions, stop at the cam/crank timing positions, then count the belt teeth between the marks and compare to Subaru numbers. also, the car could be flooded - if you suspect that, try starting while holding the gas pedal on the floor. That signals the ECU to cut fuel.

rebuilt axles are notoriously poor in quality. if they are truly 'new' (as in, new Subaru axles) I would trust it isn't a cv joint. But rebuilts often have the case hardening ground away, cheap over-size bearings dropped in, cheap grease added, etc. maybe 1 out of 10 will last. just make certain it IS the diff before proceeding to swap the trans or w'ever..

swap axles side for side to confirm it isn't the SOJ/tripod joint. inspect brakes for binding caliper. (woner why the front diff got rebuilt - anyway, there's tricky diff preload procedure I think and it may have had a short lifespan if it wasn't properly rebuilt.)

did you have the battery disconnected? sometimes a security system can lock you out - try locking/unlocking a coupla times with the remote.

fuel pressure regulator? or did new one come with replacement engine?

does the car have a filter spun-on the side of the trans? or, is it remotely mounted like our 03 OBW? anyway, you may need a new filter if it's waterlogged, it isn't an oil filter, built differently inside - that is, you need one from a dealer I think. or, if the TC was stored outside, maybe the filter is now clogged and excess pressure is pushing the fluid out?(dunno if the trans filter has a bypass)

WAIT - Fair or others, suppose there WERE water in the system after it was assembled - now, suppose water were pumped into the trans filter? Is there a paper element in there that could block flow if it got water-soaked?

so, no loss of coolant? the trans is cooled by a coil in the radiator bottom 'cap'. (unless someone has modded the car) if you let the car sit and pull the trans drain plug - is there water/coolant coming out first?

that would be a welcome idea(easy to fix) - but it's actually easier to underfill - that's why you have to check that fluid with the engine idling or it will show a level 2" higher than required. It IS important to remember - you can only drain about 1/2 the total volume. Might need to check the radiator - maybe coolant pressure pushing coolant backwards thru a hole in the trans cooling coil? It's theoretically possible I guess, just never read a confirmed failure like that. Or, is it possible trans fluid is being put into the front diff and it is puking? Doesn't seem likely - maybe the trans pump got cracked - easy to do pulling the engine in that last 1/4" from what I have read. It must slide together - if you pull it together with the bolts, something will break inside....?

the typical 5 spds are strictly mechanical. THe STI has some odd DCCD, or, some models did - still, don't think there was a FWD option on that one either. The 4EAT has an electrically controlled set of hydraulic clutches so, the fuse tells the TCU to keep the wet clutch pack disabled - no power to the rear wheels.

oh, isn't it a manual? if auto, definitely try the FWD fuse position. (not accustomed to the term gearbox for auto trans I guess - but, OP is in Spain so.....I should have asked)

well, axles will last a long time, even after they begin to click - but it's a gamble on how long. re-booting some from a junkyard that probably haven't split yet, means no exposure to grit, water, etc. so, more likely to last a long time. if you want to reboot your clickers - try swapping sides with them , MAYBE you'll get longer service using the wear surfaces previously pushed on just going in reverse.

torque bind in manual transmissions seems to be temperature dependent so - it seems the viscous unit in the center diff may be bad. the unit can be repaired, but often folks will get an entire gearbox from a wreck - often with lower miles - and swap it in. any replacement gearbox MUST have the same final drive ratio as your present trans. (or, rear diff must match the new trans.)