Ok I know these trucks get bad mpg to start with. I have been driving this truck 3 yrs with a gross evap leak and getting 13 mpg. I finally fixed it no dtc for past 350 miles well as soon as I fixed it I filled it up mpg dropped to 11.8 thought it was just ecm relearning so 188 miles later filled it up again 11.6 mpg that was with me treating it like a baby. evap is the only thing that changed b4 evap fix is after the first fill up I changed plugs. I would have thought it would have gotten better fixing that big a$$ vacuum leak.gonna change cap and rotor just bcuz I can they are only a year old

 

Unfix the fix.

 

Reset the PCM, and let it re-learn... see if that doesn't help.

 

I will pull the bat cable and do key on for a while to reset is that the correct way

 

That'll work.

 

resetting the pcm shouldnt really fix anything since the pcm is always adjusting to get the numbers it wants...after 200 miles it should have relearned regardless...
Maybe it was running lean because of the vacum leak and now that its fixed your getting what you should be at a safe air to fuel ratio?
did you use the same plugs? how about the possibility of a damaged wire or plug? any shudder in overdrive now?

 

went to the e3 plugs after the mpg drop No shudder im leary (sp) of the wire they are cheap im going to put a set of 8.5 thundervolts on it

 

you better not have thrown out your old plugs. you may need them when the e3's start dieing in 5000 miles

 

I will never buy any fancy dancy 5 dollar plugs. The will not do anything more that a 1.25 plug wont do. All advertising hype.

 

Yeah but you really start seeing some return on investment in the $18 range plugs don't you?