I recently purchased a 1990 Buick Electra Park Avenue from this little old lady. It has 76,000 original miles on it. It's in essentially mint condition. You could eat off the engine. The only thing is a few scuffs on the bumper. It's white with a soft top and red leather interior. I'm in love.
Anyway, the only issue I have with it is a hesitation that's most noticeable upon takeoff when it's first started. The only other time it's noticeable is when you rev it while in park at any time. While in park and you rev it, it's like it stumbles while the gas pedal is depressed to a certain position and then continues with no issue as you give it slightly more throttle. It's most noticeable under acceleration when it's first started. If I push the throttle to the floor it accelerates with no problem. It's only when giving it partial throttle that it hesitates.
Here's what I've done so far. I've replaced the plugs and wires (original wires and plugs were still on it), replaced top and bottom of coil pack with a spare new unit I had from my last 90 park ave. Also cleaned all battery and coil pack connections. I also had the crank shaft position sensor replaced.
As far as diagnostics go I've disconnected the TPS with no change in symptoms, disconnected the MAF sensor from throttle body and it actually ran much worse. I've also cleaned the MAF and throttle body with cleaner.
I'm at a loss as to what to do next. I know it almost has to be something electrical. One of my mechanics said it may be the computer, but it seems like it would cause more issues than just a hesitation.
Anyway, any suggestions are welcome. Thanks. Kyle