This miss feels like the engine is stopping not just missing but jerking the car for one cylinder. If I just barely hold speed it is minimized or if I step on it it will stop so I’m pretty sure it’s not ignition wires or coils etc… I would suspect pre-ignition but it’s been going on a long time ( a year at least) while I’ve been half fast trying to figure it out so if it’s pre-ignition then this is a hell of a strong engine. I have suspected a slightly sticky injector because of the working fine at more throttle.
I hope someone has a good suggestion.
Mark
Is it throwing any codes? I take it the wires, plugs and coils have been changed?
I’d throw a double dose of Techron into a full tank of Shell (BP, Mobil, Exxon, i.e., Tier One gasoline) Premium. (Be sure to post the results.)
I had a 1986 Chevy Celebrity that did something like this around town. On the highway it was OK. It turned out to be the locking torque converter that couldn’t quite decide to lock or unlock. In town with light load it was locking and unlocking all the time and quite annoying. That car had a four wire electrical connector near the torque converter which I just unplugged. Eventually I installed a relay to close that circuit only when the cruise control was on.