This is my first post! I have a pretty much stock 1989 s-10 2.5, standard trans, which I bought new, now pushing 250,000 miles. Still runs GREAT, and has given me very few problems (considering the abuse it's taken). However, it has begun to idle at about 35mph in 4th gear. I have no tach, but it sounds like the engine is running about 4X faster than it should at standing idle. I've checked the linkage, and have adjused it to slow the idle as much as possible, bu still no luck. Check engine light comes on now and then, but I've not had a chance to check it yet. Any suggestions?