I have a 250 super duty with a 5.4 liter engine, 71000 miles and a 99 model. In 4th or 5th gear with just enough gas to keep a constant speed just above idle it will miss pretty regular. If you press down it does not miss and goes on but sometimes it acts like it doesnt have what it should. I had a check engine soon light on and ran a code and it was the EGR valve and I changed it and it seemed to stop it for a while but it is getting worse again. Any ideas? No lights on now. If there are no lights on can you tell anything by hooking it up to a computer?

 

Welcome to FTE
It could be a weak coil., but it could be a number of other things too. I would first start by cleaning the MAF. ( there is a good how to article in the 97-03 forum in the FAQ thread)
A good scanner with data logging capabilities will show a misfire before it actually throws a light.

 

Thanks, I will check that.