I have a 97 S10 Blazer with a 4.3L engine that is idling very high. At startup it runs between 2500 & 3000 RPM. Did the general assumption and looked for vacuum leaks. Quite certain there is no vacuum issue. I disconnected the accelerator cable and the engine idles normally. No apparent binding in cable or throttle body. I assume its the PCM doing the accelerating. Is this a symptom of a bad MAP or TPS?

 

My guess it's the TPS (throttle positioning sensor) I have a '99 Silverado w/ 5.3 and it did the same thing and I replaced the TPS and it fixed the problem