Hi all,

My '99 Lariat Scab has been running really rough recently. It has not been driven for about 2 weeks prior, but I put a fresh tank of gas in and it's still running bad. It hesitates when I step on it, and at idle the truck is shaking.

It has about 127,000 miles on it (5.4L). It's Chicago winter up here so I am sure there's plenty of condensation buildup, but even after running it for 30 minutes it's bad. Smells like sulfur coming out of the exhaust too, do not know if that means anything. Thanks for any help.

 

CEL? Check the codes.

 

I had the same problem a few years ago. it was a miss caused by a cracked boot between the plug and COP. it was bad enough to make the truck act up but not enough to throw a CEL. with a scanner i checked the stored history and found what cylinder was acting up.

go to an auto parts store like autozone and have them read the codes. I'm not sure if their readers will read the history though. they will do it for free.

you can always romp on it and try to force the CEL to come on.