My truck 93 wants to shake and lower speeds, but only when gas is applied.

I can coast at 20 miles an hour going down an incline, no vibration at all. Give it the gas and it vibrates like hell. I cannot understand this.

Engine runs like a top sittin still,, I can red line the thing at will not move, even a little.

Any help as to what the problem might be,,, ro where to look would be appreciated

 

Hard to tell from your description.
Torque converter can shudder at low speeds when gas is applied slightly.
Sounds like it could be universal joints.