First, some history. I did a complete tune-up about two months ago. Plugs, wires, cap, rotor, coil, air filter, fuel filter, fuel pump, exhaust, had cats removed, they were plugged. Saturday, I while driving, when I hit 3rd gear there was a small sputter, it went away after the engine warmed up. today on the way home from work it sputtered very bad when i hit 4K in 3rd, and again when I hit 3K in 4th. I tried to get through it but, it only got worse. It only does this when in 3rd or 4th gear, the other three are absolutely perfect. I have run out of ideas, and I really need some help. Please.

Well first off. What kinda car is it(year, and injected or carb'd?). If I infer right, it's an EA81 because you don't mention a 5th gear.

did you replace BOTH fuel filters? One in the engine bay and one next to the fuel pump. You did say that you replaced the pump, so you might have replaced it.

What kinda plugs did you put in?

check if your base gasket is leaking let me guess 5 will do it to but you have to get up some rmps

 

if not the base gasket leaking it might be your 2nd barrel not giving it enough fuel on at full throtle

 

i had this problem with my 86 gl wagon and just went ahead and rebuilt the card fixed the problem..........but now im thinking of doing the weber swap

Sorry, 5 speed, carbed, D/R, EA82, 1987 GL Wagon. I can't find a second fuel filter under the hood. I am going to check the fuel pump tonight.

the other fuel filter is located under the car on the passenger side near the rear tire its mounted on a plate that u will have to take off to access

Sorry, 5 speed, carbed, D/R, EA82, 1987 GL Wagon. I can't find a second fuel filter under the hood. I am going to check the fuel pump tonight.