Join Date: Jul 2005
Location: Ontario, Canada
The description "running rough" doesn't give much information, but off-hand, I'd say that you have a sensor problem - when the engine heats up and the ECU goes into "closed loop" operation, it doesn't appear to like what it sees - ergo "rough running". In a lot of cases, when the TPS is acting up, you'll get the symptoms you're describing, but if that's not it, you have two very wide areas to investigate - fuel & electrical/ignition. I would recommend doing a few more tests, like fuel pressure (with & without vacuum attached) & manifold vacuum. A good description of your engine would help, including what sensors, ignition parts, etc have been changed.