89 Buick Regal Custom

I have a 89 Buick Regal with a few frustrating problems. When letting off on the accelerator the car "bucks" and seems to run poorly. When I accelerate it goes away. The car will not idle properly when in gear it will stall. All problems will go away when you push down on the pedel. I have replaced O2 sensor and fuel filter. The ECM is giving no codes.Sometimes it will idle very high after starting or after putting into n or park.

Second problem is the analog odometer. I have tried replacing it with no luck. Please help.