93 chevy c/k1500 4x4 running rich!

I have replaced the throttle body sensor and it idled down for a few cranks after, than replaced the idler sensor and it ran and idled like a bran new truck for about 5 hrs. Than It started acting up and went back to the same thing. High idle. So high you don't have to use he gas pedal it wil shift on its own if u didn't use the break.
Any idea of what I need to look at? All help is appreciated. Thank you.
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Answers
Anyway, some ideas for you:
1. Vacuum leaks can throw off fuel mixture
2. Defective coolant temperature sensor can fool the computer into thinking the engine is cold, causing a richer fuel mixture.
3. Stuck throttle plate--dirty throttle plate. Clean thoroughly using proper spray material.