1991 engine shaking

Engine Mounts are good and Secure. Do you think it could be a valve left open?

Another question about the car, when I want to speed up the car doesn't go. I push on the gas, I could have it floored and the car just slowly moves up to speed. I can get up to 30 mph no prob. But when it comes to getting up to speed faster for a highway, it takes forever. I have changed the fuel filter, put in fuel injector cleaner, and nothing seemed to help. Do you think it has something to do with my gas? Or is it the Trany? I have checked the Trany fluid and its fine, hasn't changed since i've got the car!

I highly doubt its a valve, they control the gas/air intake and exaust output it would cause a miss or bucking. It could possibly be the crankshaft bearings, a worn lobe on the crank, unbalanced driveshaft, or tranny mount. Also check your front body mounts. And as for the sluggishness, there is a good possiblity it is your fuel pump. They tend to do that before they go. Here are 3 signs u need a fuel pump (1) no gas at all going to motor (2) not enough gas getting to motor I.E. Noticeably sluggish *my boyfriend had a probe that wouldn't go over 30mph and the fuel pump needed to be replaced* and (3) car runs fine on flat ground and bucks and dies going up hill*my festiva did this, we had to push it up hills but besides that it ran fine and we had no more problems with a new fuel pump*