So my mpg's have fallen and i have noticed a difference in power. I know its not the cat because i have checked for that already. So I checked the next thing i could think of. Plenum gasket. Pulled of air box looked down tb and didnt notice pools of oil but it was dirty. Guess my question would be is it still the plenum gasket?? Does not use a drop of oil. and the filter is new.Truck has about 115k miles onit, also is a 5.2L.Any other ideas that it could be Thanks in advance Eric

 

well its obviously not the plenum if its not using one drop of oil..............

try a tune-up, I put some new champion plugs and a bottle of chevron techron plus concentrate in the tank, and the truck runs alot better now

 

i'd replace plugs and front 02 sensor. label the plugs so you know which cylinder they came out of. note if any plug(s) look worse than the others. that might indicate a leaky/rich injector.

 

do the key on/off procedure
and see if there are any DTC codes set in PCM computer memory

then consider a compression or leak down test
on each cylinder

 

i have tried the whole key trick thing but it doesnt work on my truck, I have been able to do it with every other computerized mopar i owned but not this truck, did they change it still 3 times right

 

winter blend gas can throw you off as much as 3 mpg.