Need help. I am not a mechanic, but my dealer says they find nothing wrong when they hook up my 03 F150 supercrew 5.4 to the diagnostics computer. Here's what it does:

Engine will not start at times and I must tap on the accelerator to get it started. I found out that worked by dumb luck. It does this occaisionally. Then it smokes pretty much when it starts.

Engine runs rough at idle "wiggles or chugs" at a stop. It never stalled to date. It ran fine for the first 6 months or so, but then just began acting up. My mechanic tells me this is normal for a 5.4 to run somewhat rough. Maybe so, but it didn't run like this early on.

Do I have a lemon? What can I try to fix the problem? We already replaced the ignition control modulator.

Thanks.

Bill