I have what seems to be a thermal related problem with the engine. The car is a 1999 Solara SLE with the V6 engine. It has about 93,000 miles on it. Normally the engine runs great but whenever it is driven over about 20 miles, the engine runs rough and appears to be missing. It does not do this in the Winter. I had the Oxygen sensor replaced at 90,000 and the timing belt at 50,000 miles. A few months ago, it started doing this on the freeway so I pulled it into the nearest Toyota garage and suggested they look at it right then while it was running rough. They agreed there was a problem and put it on their test equipment but could find nothing wrong except an idle sensor. They replaced that but it did not affect the problem.
Does anybody have any ideas what the problem might be?
Does anybody have any ideas what the problem might be?