I have a 1996 Bonneville SE (3.8L, 133k miles) that has started shuddering when accelerating rapidly above 40mph or climbing hills. When the shuddering starts the Check Engine light will come on but it clears when I slow down. No other idiot lights come on and the oil pressure doesn't change.
My limited auto knowledge is telling me to flush and change the filter for the transmission. I've also had another person suggest it may be the solenoid for the transmission, the torque converter, or maybe CV joint(s) going bad. The vehicle passed emissions testing just a few weeks ago so I wouldn't think its in dire need of a tune-up.
I would greatly appreciate any input that can be offered.
Thanks for the input, and it was a quick response!
I ended up taking the Bonneville to a garage. They didn't even bother to scan the codes. While I watched the mechanic hopped in her, took a quick drive and ran something that looked like a key chain along the ignition wires. He explained one of the cylinders wasn't firing properly because the wire was bad. They've replaced the wires and plugs and now she runs like a champ.
FYI: my local Part Source looked at me like I was crazy when I asked them to scan the codes. Apparently they don't do that sort of thing in The Great White North.