hi i just replaced my valve cover gaskets and now when it idles it will jump to 2,000 rpms once in awhile and then go back down, also when im driving it and let off the gas i can see the rpms jump.

 

look for leaks in the valve cover gaskets, or more importantly check the vacuum lines running over them.....

what year/size engine?

 

its an 88 firebird with a 2.8. i already checked the valve covers and the vacuum lines are good.

 

did you replace the intake plenum gaskets when you replaced the valve cover gaskets?

 

yeah all the gaskets were changed. i just rechecked all the vacuum lines and the one at the far back that connects to the lower intake has a very weak-soft feeling hose that the engine sucs shut and if i puch down on it i can her the idle go back down to normal.

 

there ya go...

a simple hose and your back on your way

 

when the motors running it feels like the vacuum is sucking the hose shut.

 

replace the hose with a stronger rubber hose or a plastic vacuum hose...

 

replaced the hose now idles at 2000 and climbs.

 

now im getting a code 21 and 22

 

code 21 and 22 are for the throttle position sensor...

you could try swapping that out with a junk yard one to see if that's the problem

 

checked my tps the voltage was fine so i unplugged the battery and it hasn't come back. today i will change the pcv and replace the vacuum lines and see how it goes.

 

good luck... I hope that solves it for you...