I have S10 that put a 350 TPI in. I got a donor car it was a 87 gta with a 700r4. I used the stock harness with motor and trans. The problem that I have is when in overdrive at say 1500 to 2000 RPM it starts bucking and surging. I put new msd wires new plugs cap rotor and fuel filter. It was no better and no check engine lights. thanks

 

Sometimes a torque converter with a lot of miles will make your car feel that way. Lucas makes a bottle of miracle trans fix that will work short term. You might try it.
Ron

 

When cruising in top gear at light to moderate load and relatively low RPM, the EVAP canister should purge and the EGR should be active. Either one of those could contribute to your problem if not connected and operating properly.

 

l98S10 hey im having the same problem u are with my 87 GTA but mine also does it at low rpm in town and has big heitation .i have changed everything u have plus tps and maf, also have cleaned injectors. also i tried the tranny fix it didnt help at all. if u get the problem fixed or any good tips plz let me know thx Trevor