It is normal. You really only notice it when you put aftermarket exhaust on. Is your A/C, heater, or defrost on? cuz it will change idle everytime the A/C condenser comes on pretty dramatically. And it comes on on all but 2 settings on the heater controls.
A swing of 700 RPMs is not normal unless your running a mod cam. I would look for a vacuum leak then go from there. You will see a slight increase in RPMs when the A/C kicks in but not 700 and if you do then something is wrong.
As I said look for a vacuum leak first then look at the IAC that is located on the back side of the TB. The IAC will gum up and cause some swings in the RPMs. They are easy to remove and clean by using some carb cleaner, be careful not to loose the o-ring or damage the end of the IAC when removing it.
I have a 4.7 and it never did it befor, it always reved a little at startup and it was normal but like I said it revs to 2000 and goes back to about 1000 but then again to about 1500 and back down to 800. nothing changed on the D and air is off. II noticed it happens maybe 4 out of the five starts in the day. but like I said, it never did this befor just started that why I think somethings wrong.
I changed the TPS with no luck, It is getting worse :cussing: now it revs so hard at start up that the valves hammer for a second. Peaple at my work told me they hear me reving it when I leave to go home and tell me I should not do that, It`s hard on the engine they say but I`m not doing it.
Please, does someone have any more ideas for me or had this problem and got it fixed? :help:
I dont want to take it to the dealer unless it`s my last resort.