My 92 3.1L RS was running rough so I changed the cap and rotor, plugs wires, fuel filter, and pcv valve. It seemed to help but now the problem is back between 2and 3K RPM it is really rough accelerating once I get over 3k it is fine. Is this a backpressure problem or intake or fuel pump? How much back pressure are these cars supposed to have and how do you check this?

 

try checking your timing. its quick, easy, and free

 

Sart this way.
EASIER.
AT NIGHT TIME, IN THE DARK, open your hood.
Make sure there are no lights on anywhere. Check for lightening sparks on the plug wires.
I think you have worn out plug wires.
IF that is good, then next look for vacuum leaks, all the plastic lines & such.
Last, is timing chain.
How many miles on the engine?
It's supposed to be changed at about 50-70,000 miles.
IF over that milage, check the above first anyway (it's free & easy) then keep going.
You are on the right trail.

IF YOUR TIMING MARK JUMPS AS YOU LOOK AT IT, the chain is shot.

800-831-0884 Northern Auto Parts
About $50 for timing chain & gasket set, delivered.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

if you look farther down this forum you'll find a good explanation of the hesitation problem i have been having....it goes over what i did....and then i took it to the dealer....you can find both posts below with suggestions if it sounds like the problem your having...i would say shoot for your 02 sensor next....