When I first start up my car and its not yet warm, when it is sitting just idling, the RPMs fluctuate up and down. This has been happening recently, used to never do this, and i just got done with all the tune-up stuff so Im confused. Also, if I put in the clutch while its doing this, it stops completely and the RPMs are stable. Then, say I'm not idling and I'm actually driving instead but it's still not warmed up, if I reach a hill and take it out of gear to coast down, it will fluctuate up and down as well, unless of course I put in the clutch, then it stops. Now, once I've driven it around a bit and it's all warmed up, and i let it sit idling, the RPMs will be fine and just sit there stable. Any ideas of why it does this sometimes (mostly when its not fully warmed up yet)?

 

Readjust your TPS.

 

Same answer as above but make SURE the engine is fully hot/warmed up or you'll be pissing in the wind.

 

alright thx, ill try that then