I have a '89 K5 with 350TBI and manual trans. The problem is that I randomly get check engine light but no codes after the light. I previously had to change MAP-sensor, IAC-valve and O2-sensor. I had trouble codes back then and got rid of them by changing all these sensors. But now no codes... /forums/images/graemlins/confused.gif If I drive more than 20-30min a row, then most of the times I'll get check engine light, but not on shorter trips. What could this be? Thanks.