Originally Posted by kansas-klx
Fuel injector o-rings can cause a cold high idle too (at manifold ports). Found that out when I installed new o-rings with my injectors. The old ones were more like hard plastic than pliable rubber. Probably only sealed up fully after the engine made operating temperature.
That's a good suggestion. They can also cause fires, too!
A vacuum leak check with carb cleaner should pick up on this.