I have a 1993 ford explorer 4.0. 4x4. Im trying to figure out why it is idling rough in parked and my rpms go up and down and acts like it wants to die. Iv cleaned my aic and t body got a new tps and i have checked all my vacuums for leaks i found my purge valve was broken and was rigged up when i unhook the tps it idles smooth. But one i hook it up it looks like the motor wants to jump out.The person i got it from said that it just needed a starter and a o2 sensor but he didnt say witch one to change. Someone please let me know.