Re: Dad's 89 Buick LeSabre unable to pull codes rough idle
My parents 88 Bonneville did this as well, even acted up when they traded it in. It didn't show any codes at all, just would run rough and then run fine, like someone flipped a switch. Odd thing was if you unplugged a sensor, it would run fine in limp home mode, but go to acting up randomly once the sensor was plugged back in. Ended up being a bad ECM, according to the Pontiac dealer.
2012 Camaro SS
03 Suburban 2500 8.1L - Tow Pig
75 MGB - eternal project
67 El Camino - Sold