last couple days i let my car warm up in the morning ( like your supose to ) and it idles fine in park while it warms up. once you put it in drive or reverse it wants to die like today i put it in reverse and it just idle down and killed itself ? and sometimes when i drop it drive and the rpms drop to like 300 and go up to 1000rpm's and it repeats itself and then it does that until i rev it and but if i dont rev it, it dies for some reason. But once i rev it and drive it down the street (already at running temp) it runs perfect. it never does any other time except in the morings (when im letting warm up) and getting ready to go school once i put it in drive or reverse it does the idle surgring ( jumping from around 300 to around 1000 rpms) any suggestions ? i just want my car to run right i know i have a exhaust leake from the Y pipe on pace setter headers but wouldnt think it would cause that only in reverse or drive ?