So when I start my car, the idle jumps up to 1400rpm, and then slowly (15-25 seconds) falls down to 800 rpm. WHY?

Also, I SeaFoamed the car on Sunday (just the intake/chambers- thru the booster hose) and now it jumps to 1800!!rpm before falling to normal idle of 800rpm.

What's going on?

Dave

 

Sounds like you made a vacuum leak.
Check your brake booster hose you were using.
Did you install everthing tight?
Did you screw up the air intake bellow? Make sure it is fully seated around the throttle body, with no rips/tears in the bellow.

 

my car does that to...... i have no idea why it does it i have checked for leaks and crap nothing??? we are in the same boat.

 

There are no obvious vac. leaks. I have been fighting a rough idle for a while and thought the seafoam might help. Should I pull the power to "reset" the IAC?

What else would cause the high start idle?

 

if it only does it on a cold start, it is supposed to flare like that, 1800 is a little high for the flare though, have you cleaned your throttle body and IAC yet?

 

When mine is cold, it also flares up pretty high. Not 1800 high but it's up there and then comes down to slowly but surely.