[B2B]

I bought an 86 Gt 5 speed that ran pretty rough so I had an overall tune up with spark plugs rotor cap etc.(Wires where not replaced because mechanic said they were fine) and it runs much better but when in 1st and second when I step on it when the rpms get up in the 2-3000 range it the car feels a little shaky or rough but into 3rd and 4th not as noticeable. Mecanic says thats about as good as it gets
without going to bolts ons (cold air,throttle body etc.)
Ive driven my buddies 89 without bolt ons and doesnt feel rough
at higher RPMs so im wondering what would be other things to try.
Thanks

[StangLX93]

considering your feeling the vibes with engine speed, your able to narrow down to engine vibration and not chassis or driveline, it could be a couple things, the harmonic balancer, or motormounts, or other mounts in realtion to the engine/transmission mounting,

i believe you should check the harmonic balancer after the years of weather or storage, the rubber band between the weight and pulley rusts up on the metal surface and pushes the weight on the balancer out of round and it creates an unbalanced balancer, and it gets worse as you increase RPM, and sounds like that your problem from your description

[spdjnky_42]

Sounds like a vibe under load something w/ engine tune or a mount