Hi, folks. My truck just turned 70,000 miles, well-maintained. I just installed a new K&N air filter, and new Autolite double platinum APP 5125 spark plugs (.044" gap). After reading posts here, I decided to advance the ignition timing from the factory 10 degrees BTDC to 14 degrees BTDC, hoping for more power & fuel mileage.

Now, as I mildly accelerate through the gears (5 sp. overdrive manual Mazda trans.), the truck jerks & misses, only in the range from 1,200 rpm through 1,800 rpm. It seems fine otherwise. My mechanic is wondering if the fuel (10% ethanol, 87 or 89 octane) and the new air filter is causing a lean burn, and perhaps non-ethanol or premium fuel is needed with this advance. Any constructive thoughts & suggestions would be greatly appreciated. I'll be taking the truck up high soon to a WY. elk hunt & would I'd like to resolve this problem before then. Thanks much.