LEXUS4MEtwo

I picked up a nice 1993 400LS with 48,000 mile example but had some quick issues. They started with the intermittent tach/speedo issue. After about 400 miles it went into limp mode. I was in Vermont so I took it to a local Toyota dealer in White River Junction, VT. They decided I needed a new/rebuilt ECU. They gave me the part # of the ECU 89661-50042 which was in the car. When the replacement came in, the Toyota dealership must have finally cross referenced the correct # ECU part 89661-50140. It was replaced and all seems to be good after 1,500 miles except the speedo and tach still intermittenly work. My guess is that the ECU has nothing to do with the speedo/tach issue mentioned here. I'm still concerned that it might, but I'm begining to think it is the stuff you guys mentioned behind the dash. Your opinions please, the local service manager thought it eas more likely the stuff in the dash and not the main ECU being the culprit. Thanks, Rich in Wisconsin PS, I also picked up a nice 2004 430LS with 83,000 miles. So far, so good on that one.