i got a 95 with 3.9 slt and when i am driving down the road at a consitant speed like 55 at 1800rpms it surges like it is starving for fuel i have replaced TPS,MAP,fuel pump twice,and ran fuel cleaner through it and it still does it and i have cleanded the IAC any help would be great

 

Have you checked for vaccum leaks did you replace the fuel filter after the fuel pump. I recently replaced my fuel filter and it helped it from acting like it was dieing after I let off the gas. Also when was the last time you changed your air filter?

 

i havent really checked for them i have plugged up some holes and i put a new air filter on it back in september it is clean and is there another filter besides the one in the tank cause i havent found one

 

Mine was between the cab and the tank on the left side on the inside of the frame rails it should be around where the parking break cable is.

 

The '91 and the '95 are different in that the '91 has an in-line fuel filter (smart) and the '95 does not (not smart.)
The fuel filter on the '95 is part of the fuel pump assembly.

I'd suggest checking on those vacuum lines...

 

Thats wierd you would think that they would want an line as to make servicing easier for the mechanic at the dealership.

 

Ya it would make more sense, but they figure that you will have to spend more to replace a simple part by replacing the entire unit. Extra $ for part, labor, and shop costs.