bad mileage help

This past July I put a jardine cat back exhaust on my truck. I wasn't looking for much performance gain but mostly for sound. Surprisingly I found that I got a bit of a mileage boost until recently.

What I have noticed recently is that the truck feels a like it has less "oomph" at the low to mid range rpms and I have to keep it around 2900 3000 rpms to keep the truck at a constant speed. I started putting in 89 thinking this might help and it seemed to for a while but now it is back to feeling weaker again. The exhaust sound has also seemed to get a little louder. Any ideas what the issue is here? I also have a TRD CAI with an AFE Pro Dry filter. As I recall from last time I was under the truck the exhaust was bolted on not welded. Is it possible that it has loosened up and I need to tighten it and or get it welded? Thanks in advance for any help.

 

Whats your milage, have you changed your plugs, computer throwing any codes, right foot get heavier, driving on snow/ice, tried a different gas station?

 

exhaust leak

 

mileage is at best 18 highway and depending where I'm at on regular roads any where from 13-16. Haven't changed any plugs, computer isn't throwing any codes, in VA so not much snow/ice driving and I try to use the same gas station every time (but I did move from NY to VA in august, maybe gas composition is different down here?).

In terms of my foot being heavy, I've noticed that if I accelerate quickly through the lower rpms I seem to get a better avg mpg since I am at the lower rpms for a shorter amount of time. This hypothesis seems correct but please correct me if im wrong.

 

is there a way to check this or do I need to have it welded and then see if I notice a difference?

 

welding is not needed. just go from the headers and work your way down to the exhaust tip. its not the easiest thing to find but it could be as simple as a gasket replace or tightening a bolt.

 

Nobody mentioned a dirty MAF

 

and what am I looking for exactly? Just any space that could be leaking exhaust?

 

hmm I remember reading somewhere that they mentioned doing that after installing the TRD CAI and I don't believe I did it then. At almost 60,000 I'm guessing that should be an option I consider. Even if it's not the fix it won't hurt right?

 

Correct, just be carefull not to damage sensor

excuse my misspellings, reply sent from my phone.

 

any one got any other ideas? Or maybe someone who has had the same thing happen and found a solution

 

Clean Maf, change air filter, replace sparkplugs, run injector cleaner, inflate tires and get a more scientific means for monitoring fuel mileage. Not to mention Fuel formulas from winter and summer are always changing too. With out a proper means to record driving habbits and other extranious variables its hard to tell what's going on at ur end.