My sack of replaced bad capacitors is getting bigger every week. Two ecu's this week, one was really bad where the copper trace was corroded away, along with the leg of one of the capacitors. It's not the only thing that can possibly go wrong, but it's so common that it's one of the top problems on the list. Usually when the engine runs great for a period of time, then starts running like crap seemingly for no reason, it's the ecu. 90% of the time, new capacitors alone fixes the problem.