My 2.8 is running smooth as can be - except at around 2000 RPM, I got this vibration. This is sitting still, in neutral or going down the road w/ no load on the engine. If the motor is under load it's not there. This is a carbed engine / no ecm. - electric fan, basically a S10 truck engine. I changed the harmonic balancer, checked the torque converter bolts.
The rest of the time its smooth as glass, I'm stumped.
R.J.