I have a 93 pickup with an erratic idle, when the car starts (cold outside) the idle is high (around 1200 rpm) but as the car warms up the idle goes up to around 1750 to 2000 rpm, and then bounces between 1250 and 2000 rpm. On hot days it doesn't have an issue at all, but as it gets colder (like 50 deg outside) the idle goes up to like 1500 rpm, and when you step on the brake you get the erratic idle again where it goes from 1500 to 2000. I have tested the coolant temp sensor (good), brake booster (good), O2 sensor (good), fuel pressure (good). The only thing I have not tested is the intake air temp sensor and the mass air flow sensor because I think the air temp sensor is in the mass air flow sensor. Any ideas are welcome, and thanx in advance!

 

Is this a 4 cylinder or the V6?