[jfrabat]

I think the TPS sensor is busted. With the engine relatively cool (as in I leave it off for about an hour), the idle is fine (about 1.1K RPM). Then, once it warms up, idle goes up to between 1.6K RPM to 2K RPM, going up about 150 RPM every 3 seconds until it reaches 2K, then droping back to 1.6K and doing this cycle over and over.

With the engine cold, if I give it some gas, it will rev up fine, but once the idle goes down the drain, if I give it gas, it stalls. To drive it home, I had to have a VEEEEERY light foot, as it would rev up as long as you did so just a tily little bit at a time (I was feathering the clutch much too much for my taste, but it was either that or paying for towing!).

I got a CHECK ENGINE light driving home, but I had to return to work, so I did not have time to read what the problem was. But I'll check that tomorrow (I think the odds of it being the TPS are high). I still have the TPS from the 4.0L TB, so I can try that one first (if the problem IS the TPS), and if it does not work, I can always get a new one and replace it (the one on the 4.0L TB looks a bit beat up!).

I also know my fuel system is not up to par (when I removed the injector rail because of damage, it was filled with slidge), and I do plan to (1) clean and seal the tank (I got a POR-15 kit for this purpose), (2) replace the fill and vent lines, (3) replace the fuel pump and in-tank fuel filter, (4) replace the in-line filter (I did this about 2 months ago, but it looked like it was NEVER replaced!), and (5) replace the fuel rail, FPR and fuel injectors. I already got all the parts (about $300 worth!); now I only need to find the time (just the POR-15 tank tratment takes a good couple of days to do because of all the waiting time involved!). But I know this is not the problem, because before the TB swap, everything was working OK (as long as the temp outside was belos 85 degrees!).

Felipe

	Throttle position sensor A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in an internal combustion engine. The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the butterfly throttle valve. The sensor is usually a potentiometer and therefore provides a variable resistance dependent upon the position of the butterfly valve (and hence throttle position). The sensor signal is used by the Engine Control Unit (ECU) as an input to its control system. The ignition timing and fuel injection timing (and potentially other parameters) are altered depending upon the position of the throttle, and also depending on the rate of change of that position. For example, in fuel injected engines, in order to avoid stalling, extra fuel may be injected if the throttle is opened rapidly (mimicking the accelerator pump of carburetor systems).