1200-1800 rpm vibration
 

Noticed when at the above listed rpm's the motor seems to vibrate the truck pretty good. not misfire bad, but enough to wiggle the seat. its on a fresh tune up, and distributor, runs fine otherwise.

ideas on places to look?

Did you check your motor mounts?

i didnt suspect mounts because while under the hood, revving the motor it doesnt move excessively, i will double check them tomorrow on the lift while im doing some other work though

If the mounts have never been replaced, there is a good chance at least one of them is bad. This is common. If it does end up to be the mounts, somewhere on here there is a link to some after-market mounts that are not only more durable, but of a better design for installing. Also, give yourself plenty of time to change them because Blazer mounts are the hardest to change I have ever experienced (though I am only a "shade tree" mechanic").

Is it only when the engine is under load, or all the time?

i notice it most when im revving it to warm it up, or at low speeds

Sorry new to this, first Ford or Chevy?
Year, Make and Model.


"not misfire bad" What the heck does that mean ( more info please ).


New problem or old problem.

A spark plug wire not installed correctly? Spark plug with a cracked insulator? Cap/rotor not installed properly?