Ok so i cant seem to find anyone that has this problem. i have a 1990 s10 blazer 4.3 auto 2wd. when driving down the road cruising at 50-55, the engine will stop, but not completely. i can give it gas and it will accelerate, but when i try to hold a speed it stops firing, and even backfires some. so it is not a complete shutdown. as long as i am trying to accelerate it seems to run fine. i have a steady fuel pressure to the tbi, injectors look to be spraying fine. hooked up a old obd1 computer to it and dont see any loss of signal from any of the sensors. no noticeable dead spots in the tps. seems like i am loosing spark because when it happens the o2 sensor reads rich and fuel trims drop way down so the computer thinks it is running rich, but i would think that is because it is not burning. the coil, icm, ecm, iac have all been replaced and it will run fine for a day or two then act up again. i was also loosing voltage so i changed the alternator and the main battery ground wire and i am getting over 13 volts from the alternator. when it does act up i have noticed that the volt meter on the dash is reading very low. i am at a loss at the moment and dont know what to check.