Truck stumbling... stuttering...

[Longshot270]

Originally Posted by RGSMDNR

I fill up at Costco so not sure where they source their fuel from. Im also running a 89 Octane tune but 87 fuel and am turning the timing back 1 degree as per required.

Ok, go to Shell or another top teir brand. Not all fuel blends are equal. 9 times out of 10 it pays to spend more per gallon more for higher quality fuel.

For me it means up to 1 mpg difference...or nearly 10% increase in mileage for spending 1% more in price.