johnathan25
Junior Member
I've been having a really rough idle on my 06 mustang with the 4.0. In park it doesn't idle nearly as bad, but it's still rough. When put in drive or reverse, the rpms drop so low that it nearly stalls out. On average it idles at around 550rpm at operating temp, however when put into drive or reverse it'll drop down to 400 or lower, as well as at a stop light it'll intermittently drop down to 400 or lower. While driving up the road it drives nearly perfect with no issues. I'm getting a p0171 and p0174, however I cannot find the cause. There are no vacuum leaks, no exhaust leaks, intake manifold gaskets have been replaced, maf has been cleaned, throttle body has been cleaned, fuel filter has been replaced, and both o2 sensors have been replaced. Ive also reset pcm and did throttle and idle relearn after doing all of this but to no avail. I'm stumped as to why I'm having this idle problem. Any insight would be appreciated!