Okay I have been dealing with this car a little trying to help my mom out with it.
When we first got it the trans would pause going into gear and especially shifting from drive to reverse, it would slip going into gear and the awd would take a minuet to engage letting the front wheels slip. I found out about a TSB in 91 auto trans for clogging radiator coolers and a magnetic filter that goes inline to the trans cooler. We replaced the filter and the radiator (since the old rad blew up) and it started shifting better and there was no delay in engagement. Now a little ways down the road It's showing the same symptoms again, delayed engagement mainly.
I'm just wondering if the trans needs to be drained and filled (yes I know to do it three times with a drive cycle between drains) before I put another new filter inline and if I should replace the internal screen filter while I'm at it.
Also is it possible the low line pressure could have caused the awd slip when we first got it? It doesn't seem to do it anymore, but I haven't really driven it in slick conditions yet. Or is the rear clutch packs going out clogging up the filters?