[oldchevy]

91 c1500 4.3L 170,000

I just passed my smog test, but since the last test my idle 775+/-425 HC ppm reading is up higher than it has been..only 113 ppm (limit is 220).

What repairs can i do to lower the idle HC reading?

My high rmp HC reading (2500+/-300) is reading an awesome 41 ppm compared to limit of 220.

Any fixes to bring down the standing idle HC reading.

ty