Nice site, first time posting. Unfortunately I can't seem to filter on a specific area.

Specs: '94 Blazer, 4.3, Vin "W"

Problem: Upon warm up the engine purr's, then when driving at any speed the engine shudders and tries to clear itself out as speed increases. It acts like an old Holley carb that loads up. Any suggestions out there?

Areas inspected/tested: Replaced fuel pressure regulator, fuel pressure within spec's, Cleaned out the IAC, changed O2 Sensor. CPI and nut kit looked fine-no leaks.

No known codes displayed.

This one is stumping me, I'd appreciate a path to look into.

 

Fouled or gummed plug(s)?

 

Changed the plugs already with OEM Ac Delco, I should've added that to the items tested/replaced.

I have noticed that I have to clean the distributor cap-points every 4-6 months. I use a cordless dremel and a small wire brush attachment.