Gear shift lag, poor MPG

[Eric90XJ]

I have a few things wrong with my 98' automatic V6 XLT, namely the gear shifting. It feels like it is reving up the RPM way too high at each gear change. I will step on the gas and it feels like its struggling really hard to keep up and the engine is reving up way high and missing its shift then it will finally do it and drop down but still high. Other problems include a slightly rough idle, with just a little stutter that is almost unnoticable. Mostly, this is eating a hole in my wallet from the loss of mpg. I just replaced the IACV, which was the only code the engine was throwing. Anyone? Fuel system issue? Fuel filter hasn't been changed in a couple years might start there. Just seems like this is a bigger issue then a clogged fuel system, I hope it's not the tranny.

 

[Explorer '96]

To raise your mpg a little bit is to first use a voltage meter to check all of your emission control sensors and if one is bad or not at where it should be change it. Also cleaning the inside of some parts in the engine helps. Because of all of that I gained a few more mpgs.