89 GA drops RPMs and almost stalls when shifting into reverse (automatic). RPM recovers after some "shudder".

Have also noticed that there is no longer a pressure "release" when removing gas cap. Is there a problem with my PCV / canister system ?

Noted both symptoms at around the same time.

...Mac

This a 4 or 6 cylinder Mac?
This start all the sudden, or just progressivly getting worse?

Are the plugs & wires in good shape?
Right off I think of the tcc in the trans going bad,
does it hav other simptoms when driving or when stoped in traffic?

If the trans fluid & filter hasnt ever been changed,
its probly time. This might clear the stalling up.

Your fuel system may just hav a leaky canister,
or one of the clamps hav a leak.
Might check the fill neck and other hose clamps under there for tightness.

Thanks for the reply.

Its a 4 cyl 2.5. I have replaced the plugs, wires, and coil packs. When it gets up to speed, its ok. The shudder occurs sometimes just coming to stop, but is worse when shifting. The trans fluid and filter have been changed in the last 20,000 miles. The car has about 130,000 miles on it.

~Mac

A shudder or vibration when accelerating is usually caused by the CV joints.
Might want to check or have them checked out.

Good Luck.