Hello, I have a 96 with 125K. At idle, the engine runs at about 900 RPM and every
3 seconds (approx) the engine speed will spike up 300RPM for a split second, then drop back down again. It also happens at other engine speeds - cruising at 30mph, it still ramps up every 3 seconds and the truck lunges forward very slightly. What in the world could be causing this? The only engine/emissions problem that I am aware of is that I've been told my catalytic convertor needed replacing a year ago, but I haven't gotten around to replacing it yet. Thanks for any assistance you can provide.. Brian- posted
20 years ago