Also look for any cylinder ballance problems. All it takes is a missing vacuum fitting at one port or a small leak to get one cylinder to run lean enough to make the motor shake.

I have put a scope on the O2 sensor at idle as a way to pinpoint a vacuum leak. You could see the blip in the voltage as the one lean cylinder fired. Turns out I forgot to plug a port vor the cruise control on the intake manifold that was located in front of cylinder #3.

A compression test never hurts just to be sure.

Kevin

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...