I went racing this past weekend and when I put the normal tune into the car, I noticed the idle dropped down to 400 and I don't think I touched anything. My car is basically stock. It runs ok except for the idle. So I went back to the ecomomy tune for the ride home, drove home (2 hrs) and came off the highway and it was still at 400-500. So tried putting it back to stock and now it surges when cold 400-800rpm. I know about the dealer thing and the warranty, but this car ran perfectly for a year with the tune until Saturday. Anybody help? Should I try raising the idle?

 

ok first i'd spray the MAF with
appropriate cleaner....

if that doesn't fix your idle issue, then
throttle body would be next to clean

 

I have a white V6 and it has always idled perfectly until about two months ago. It idles up on start up as normal but once the enginw warms up the idle drops to 550. I took it to the dealer and they told me that the idle was within normal ranges. Could this be the MAF?