[oldwagon2]

My 86 GT wont idle when it's cold, runs rough, surges & constantly stalls, it's a little better when it warms up, but there a dead/flat spot in acceleration @ 900-1100 RPM. I've tried several different TPS's w/ voltage settings from the mythical .98v to 1.35v combined with varied curb idle setting for the throttle plates. I can vary & improve acceleration torque but I cant get rid of that lower RPM dead/flat spot. The voltage doesn't vary or drop during this dead/flat area. It behaves like a vacuum leak but I've clamped off all hoses coming from the upper intake/plenum chamber & if it's a vacuum leak I'm looking dead at it and can't see it.
I changed valve cover gaskets several years ago which involves R&R of the upper intake, but it's almost impossible to put it back together wrong. This would be a likely area for a vacuum leak, but you should be able to spot it without tearing it back down. All diagnostic feedback is welcomed. Thanks

[89coupe]

Run the codes first

DIY KOEO/KOER/Cylinder Balance Self-Test Procedure

[tbeneteau]

Not sure, but might be the MAP sensor. (top of the firewall, driver side) Mine would barely run...but when I squirted fuel into the intake it would run alot better. Replaced the map sensor, and it was like new. (Unfortunately, these are almost impossible to test, because they put out a certain frequency to the computer based on manifold pressure.)