ok well i started the blazer this morning and it stayed at 1500rpm and would not come down after letting it warm up for 5 minutes, so i let it run for 15 minutes with same results. throttle body is cleaned with brand new IAC all vacuum lines are new.sometimes when i turn the key off then start it again it will be normal and sometimes it wont. also when i turned on the heater it blasted some snow particles at me is this normal, yes it snowed last night. first time thats happened to me though. the wierd thing was when i dropped it in gear it went to normal idle rpms where it should be when warmed up in park. im confused on this.

 

Throttle sticking open?

 

not sure will check tommorow. should i grab where the cable is and make sure that its all the way down or tke the intake off a little and see. and also running or not running?

 

While running

 

It is not completely necessary to have the engine running while you check the throttle body for binding. If you do check it with the engine running, just pull the throttle closed and listen for a change in RPM. With it off, you can remove the intake duct and move the throttle through its full range of motion, feeling for binding anywhere in that range, specifically near closed throttle.

Another thing to consider (and probably just replace) is a faulty PCV valve. If this hangs open, it would act just like a vacuum leak, but it would be sucking air out of the crankcase instead of outside the motor. On that same thought, if the brake booster were to have a leak, it could do the same thing.