Lately, I've noticed that the tach on my '86 IROC tends to fluctuate around idle. In addition, the car has been difficult to start lately (sometimes stalling right after it starts). I'm not tripping any codes, but I did install a new tranny two weeks ago... I didn't seem to notice this until just a few days ago. My car idles around 500 RPM. I have a Pro-Built TH-700 with a 2,400 RPM torque converter. I really haven't noticed any difference in performance, but that could be because I'm benefiting from the new transmission. After about 2,500 RPM, the fluctuation seems to go away. Any ideas?

EDIT: I forgot to mention that it smells like fuel every time I start up my car... like really strong.

 

First, the idle RPM is too low. A sluggish IAC can cause your symptoms. Try cleaning the TB and IAC, adjusting minimum air, and setting the TPS. Check this thread for details: https://www.thirdgen.org/techbb2/sho...hreadid=134125

 

Thanks Vader! I'll be sure to try what you suggested.

 

Once you solve the idle issues, the fuel odor on startup may or may not be solved. If not, start by checking the cold start fuel line and injector.

 

Hey Vader you seem very kind and knowledgeable.
Question, got an 84 305. My acceleration sucks! just got a rebuilt carburator, new plugs, wires, cap and rotor. I thought this would solve my problem , but it didn't. Any suggestions?

Thank you!