1993 Ford F-150 F 150 Engine Vibration while stopped in driv

F 150 Engine Vibration while stopped in drive!

My 93 F 150 2 wheel drive, 4.9 liter I-6 engine, C-6 Auto Trans with about 130,000 miles
has gradually over the last several months developed an engine vibration problem when
stopped at red lights, or stop signs with foot on brake, and in drive or reverse.

The vibration is strong enough to be felt through the seat, and can also be seen as the
driver's outside door mirror shakes.

When placed in neutral or park, there is no significant vibration.

During the first 5 minutes of operation (ie when cold) there is no vibration.

My Garage mechanic has changed the plugs, ignition harness, rotor and distributor cap with
no improvement. He has now added a bottle of Injector fluid cleaner to the gas tank.
So far that has not helped either.

I would appreciate any suggestions. You msy email me directly at floch1@rcn. Com if you wish.

Frank