I have a 94 sts the car only shifts up to 2nd gear she wont go into 3rd or 4th My local tranny shop says my 4th gear is shot. the car has 150,000+ miles on it looks and run about fine otherwise

I doubt it. Get a 2nd opinion.

What you describe sounds like a solenoid or solenoid connector problem.
Solenoids can be replaced w/o a teardown.

Highly possible broken shift solenoids, lower pan has to be removed to check them. If one is broken, they can be replaced and may fix your problem without major repair.