rpm fluctuates at idle

i recently changed my spark plugs, but not the wires, (it's happening this weekend). the weirdest thing is my temp gauge has started occasionally go up and down....i checked my coolant level in the overflow tank and it was good......the only things that i've worked on in the past months: new belts, plugs, oil.....

 

have you cleaned your throttle body?

 

Seafoam it.

 

Hmmm, the temp thing is odd, but did you double check any and all vacuum lines you may have disconnected or bumped or damaged or reconnected incorrectly when you were doing the other work? They can cause idle problems.

When does the temp fluctuate? While driving at constant speed, or at idle? And by how much? This could merely be coincidence.

When was the last time the coolant was changed? Maybe it's time to do that, and replace the thermostat and even possibly hoses that may be collapsing and impeding flow. This happened to my old truck at highway speeds.

 

For the temp thing, change out the thermostat. Fast & Easy.

For the rough idle...check for cracks in you rubber air intake pieces...and of course vac lines. 99% sure that what it is, an air leak caused by you removing the pieces when you went to change the plugs.

 

my idle is a little below 500 rpm when its properly warmed and relaxed

 

thanks for the replys i will seafoam, clean the iac, and flush fill...it's great to check with rest of the world to make sure i'm not missing anything.

 

a few weeks ago one of my spark plug wires went out and i didnt know it the rpm went down under 500 at idle and would make a bad noise, this may be your problem i replaced the wires for about thirty bucks and it was runnin great afterwards. FYI: dont touch the wires while the truck is runnin. hahah itll give you a bad shock