Hey guys my first real post.Yesterday morn. I was at a stop light and my truck
started to vibrate.I put the trans in nuetral but it didn't help.When I got to work I checked the trans. fluid and seemed alright.(First thing I thought of).Drove home and noticed that while driving it started at about 1100 rpm and went away at about 1400 rpm.This morn.when it started cold on high idle it did the same.Seems to smooth out at low idle.When I got home I popped the hood and had the wife give it some gas to check motor mounts.Those seemed OK.Engine shakes at same RPMs as above.The truck is a 95 F150 4x2 5.0 Auto Shortbed.
Last tune was 2yrs ago.Possible fuel injector going bad?Thanks in advance for any help you guys can give.Frankbank

 

Check the plugs and wires. These things have a bad habit of shorting the #7 & #8 wires. If it runs ok in other RPM's, you can safely rule out the fuel flow. You also may want to pull the distributor cap. I put less then 3000 miles on my truck last year but when I pulled the cap, I scraped a bunch of buildup off of the connectors and the rotor. Hope this helps, good luck.

 

ive had a similar problem with my truck (89 f150 2wd) all it was is a couple of plug wires came loose and still got connections some of the time. when i accelerated slowly at a low rpm it was missing horribly, i dont know how the wires came off but they did somehow. hope this helps

 

sometimes the rubber on the plugs gets air trapped inside and when they heat up they will raise off the terminal-sounds crazy don't it???? but air will expand

 

If it's a "vibration", and not a "miss/vibration", (listen at your tailpipe for a miss), then possibly it's your fan.

 

It's fixed.I pulled the distributor cap and checked it and the rotor.The rotor was black and the contacts in the cap had whitish powder on them.I cleaned them up and now shes purring like a kitten.I also found a broken loom and one of the spark plug wires was touching the exhaust manifold.Time for a tune up and some better way for holding the wires in place.Thanks again for all your help.Frankbank

 

Ok, so when you do the tune-up be sure to use Autolite plugs, wires, cap & rotor (bronze tipped) not aluminum and gas and air filters. As for the wires I use the generic plastic ignition wire holders that you can get at any good parts store. I've seen some guys use tie wraps. Just be sure to trace the wires away from anything that could cause them to short out. It works for me. Good Luck!!