I put my '87 K5 in the shop for an emissions test. The report was hydrocarbons were too high to pass the test. Shop thought replacing the leaking TBI unit gasket would lower the numbers. I gave the shop the OK and the work was done. Hydrocarbons dropped and the truck passed the emissions test. Driving the truck home it failed to idle. Runs strong at all RPMs but stalls at 9 out of 10 stoplights. It rarely stalls if in nuetral and coasting. Seems I must be sitting still for it to quit. After it stalls, I hear the fuel sending unit run for about 2 seconds. It re-starts every time with just a bump of the key. I checked the ECM for trouble codes when I got home. Code 42 (Elec. Spark Timing) was in memory. I removed/cleaned every connectin within site of the EST and then reassembled all with dialectic grease. Removed the battery cables to erase ESC memory and cranked her up. No more codes in memory, but still will not idle. Seems to be more a problem after operating temperature is reached. It is no longer fun, balancing my feet on clutch/brake/accelerator pedals on the hills of Virginia! Anybody have any suggestions? Thanks.