I have a nice 1988 Audi 80 with less than 100K that just developed a problem. It starts and runs great until it gets warm, than starts missing. Like clockwork when the temp gauge gets to the mid-point line between cold and 1/2 point it starts missing and get worse as it gets to the 1/2 way point. I have replaced the temp sensor for the computer (lower one) and this has not helped. Any ideas??