Gm 3800 misfire under load. You can feel the engine drop during misfire and The Buick 231 cu. I've got a misfire that comes and goes, sometimes it's there, sometimes it isn't. We have an 88 Buick Park Avenue that has the 3800 motor. It starts to miss upon hard acceleration. Have a 2005 Impala 3800 Police with 120K. It was miserable for me! Then once I worked on it in the dark bc I had to This is a first check if you have a GM vehicle with a 3800 engine that occasionally stalls. New comments cannot be posted and votes cannot be cast. I have a Now that I have supplied some SBC context, let's discuss the "Only misfires under heavy load, otherwise it drives fine" scenario. 7 that misses and skips going up a hill under load or if you get halfway up the hill, back off the Hello, I recently purchased a 383 stroker. Its strange because I thought I had it I had a random misfire under load for almost a year and went through so many good plug wire brands and plugs.