Hi All,
I have a 2000 Exp w/5.4 (87K). I just started noticing that during my cold start and initial 5 minutes of driving I have a miss, kinda cuts out like lack of fuel? After it warms up for about 5-7minutes, the acceleration is smooth. No more problems after it has warmed up. I have no codes. Plugs and COPs are 10 months old. MAF cleaned, new IAC, TB cleaned already. I was thinking maybe my Coolant Temp sensor could be bad. Anyone know where its at? or has experienced the problem I have.

Thanks,
Rob

 

Sounds like you've done just about everything simple.

Some vehicles equipped with a 4.6L or 5.4L engines may exhibit a rough idle/miss after start-up in cold ambient temperatures (less than -12°C/10 °F).

This may be caused by a roller finger follower(s) being dislodged from the valve.

This could damage the camshaft, roller finger follower, valve, retainer, etc.

There is a procedure available to service this condition if you think this might be the problem..

 

I never had any excessive valvetrain noise or the sort. Its been garaged kept for the last 4 years, so it starts up initially at 60F the last several weeks here in Houston, TX. One thing that I forgot to mention but didn't think it had much relevance since O2s aren't in the picture untill closed loop, is that I had borrowed a Nemisys scanner and noticed that the O2s after the converter were not switching at all. They were reading "RICH". My buddying is going to lend me another scanner in a couple of weeks as I was trying to pull Mode 6 misfire count.