Major Idle Problem.

So here goes. I drive a 91 SW21 MR2 with a full 3SGTE swap, axles, engine, tranny etc. Also has a mini pen size turbo timer that sometimes fails to time the turbo. Car ran fine with no problems but after about 20 minutes of driving last night the idle jumped to 2200, then another 10 mins and it jumped to 3100, getting worried I shut the car off and let it cool for 20 mins, engine temp was about 3/8th on the gauge. After letting it cool got back in to head home, still at 3100, 10 mins of driving towards home and it spiked to 4200 rpm, garaged it and cant figure out why its doing this and cant afford to pay 140 dollars to get an ultra low clearance tow truck to run it to a shop that charges another 100 dollars to run a diagnostic.:banghead:

Any help would be ever so appreciated.

Elijah~