OK, the car in question isn't an F-body, its a 1988 Plymouth Sundance, 2.2L TBI, 5-speed trans. I figured I could get some help here since some of you guys have TBI-equipped engines and figured you'd know more than me about TBI. Little history: car has around 80k miles on it, never had AC from the factory, I keep a good PM schedule, and it has new IAC and TPS and fuel injector. Here's the problem: sometimes when I am idling, the idle will raise up to anywhere between 2000 RPM and 2500 RPM. It doesn't do it all the time, only sometimes, but it makes no difference if the clutch is engaged or disengaged, it has done it both in open loop and closed loop. It has done it in good weather and bad, with headlights on and no, with heater on and no, done it in summer and winter. It can go a week or two and be perfectly fine, but once in awhile, the idle will mysteriously raise. Then I can take off fine, but say I am in first and accelerate to a shift point, around 3k or so. If I clutch it and don't shift, just hold the clutch, it will hover around 2k - 2.5k RPM, it won't drop all the way down like it should. Also, when it is idling high and I shut it off, the car will diesel (continue to run with the ignition off and the key out) for a few seconds. Could it be the vehicle speed sensor? A stuck throttle cable? I don't think it would be a vacuum leak or anything, since it only does it once in awhile. And if I'm driving long enough, the problem will go away by itself, but it will never remain idling high for the same amount of time. I really am stuck and would appreciate some help from all you TBI gurus. Thanks