timing problem??

I have an 88 Olds Cutlass Supreme and I'm having problems with it loosing power when driving. I just corrected the timing (supposed to be set to 20deg) and when I rev the engine up the timing decreases by up to 8deg to 12 until I let off the gas an it returns to normal. Isn't it supposed to advance the timing what you accelerate???

It accelerates a little sluggish, and sometimes it will not go above 65. Also around 40-43mph it will loose almost all power and I can't get it to go any higher, then I have to let it slow down to about 38-39 and then it will accelerate above 45. It seems as though around 42mph if you let off the gas and step on it, it will not go any faster, but if I start accelerating at a lower speed and keep the accelerator in that spot I can get it faster. Also if you push the pedal down too far it also looses almost all power and will not go any faster. Any suggestions anyone????

-Fubar

Sounds backwards to me. timimg should advance when the engine's rpm is increased.

the spark advance behavior you describe sounds wrong... but before you mess with that too much, check for a fuel delivery problem (plugged filter, etc). Is that car carb'd or fuel-injected?

It seems to be getting enough fuel when I look into the carb, I replaced the fuel filter justs in case and it didn't change anything. What would cause the timing to reverse like that???

-FubarOptik

I assume that you looked into the carb with the vehicle stopped, not at 40mph+ where you have the problem? Does your car have only one fuel filter? Many of those 80's American cars have two inline fuel filters. Often the 2nd is right at the base of the carb, where the fuel line comes in (looks like a fuel line fitting or part of the carb).

sounds like it could be the downshift lever if its an automatic