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I recommend you calibrate the TPS properly, it takes less than a millimeter for it to end up out of alignment. The fact that there's not code 51 present id a fair sign but it doesn't mean that it's not adjusted too far the other way causing the IDL switch to remain closed while the throttle is open. A code 41 will occur if wiring or TPS are bad... or the ECU, but they're pretty robust and seldom the problem. A code 41 will be stored if the ignition is turned on while the TPS is disconnected too, so try clearing it and see if it is recurring. TPS are wear components too, while they may test well with a basic meter they may still be in bad shape... but they are just a trim sensor; You can drive without one but your idle and throttle response will suffer.

Have you tested the cold start time switch, the ECU coolant temp sensor? Have you inspected your vacuum hoses recently? Have you checked the ignition timing?

A mild exhaust leak isn't going to affect your idle at all... boost will suffer terribly and you'll be pouring a lost of uncalled for heat into the engine bay. There's also the risk of it entering the cabin.