1997 F-150 4.2L V6 Chatter and a miss?

[aeriojunkie]

Okay, so my father-in-law has a 1997 F-150 with just under 97,000 miles on it. He has owned it since day one and it has always been taken care of and had regular maintenance done on it. About a year ago, he started noticing two things:

1) He has a bit of a miss while driving the truck at about 70 mph or higher. It doesn't show up until you are driving that fast. While driving you can feel the truck jerking back a little bit with you. It doesn't seem to be rhythmic or anything, just here or there. I figure it is plug/wire related, and we are going to try that next month when he gets his pension check. If anyone else has any ideas, let me know.

2) The other problem also started about the same time. If you get on the throttle heavy, like say trying to merge onto the highway or something, it makes a somewhat high-pitched chatter noise when the RPM's get into the high range. The truck doesn't have a tach, so I am not sure what RPM's, but it is nearer the high side. I borrowed it yesterday and drove it to work and back and could really hear this. It also seemed to happen if you are cruising at a high speed and let off of the gas, you could hear the chatter noise for a couple of seconds. It would make the noise again when you would reapply the gas. He said that it sounds like lifter problems, but I am not real familiar with internal engine sounds.

The check engine light isn't coming on with either one of the problems, but I haven't had the computer scanned to see if there is any codes stored in there anyways. I plan on having the parts store scan for codes when we buy the plugs and wires. Thanks in advance, and any and all help is greatly appreciated.