Need help again guys..97 GA 2.4L bad gas milage..what to do?

[Nickleahy23]

Alright well the car has started to get really bad gas milage..seems like every time we drive it we use 1/8 tank no matter where were going..Now here is some info on the car..

97 2.4L 124k miles, auto trans
replaced plugs, fuel filter, pre-cat o2 sensor seafoamed car, fuel injector cleaner in tank
Ive done the suck test on the FPR and it passed. Also cleaned the plug for the tranny to maybe fix the slipping, no luck. All hoses seemed good for vacuum.
Alignment is good and tires are new and at the right pressure, so thats not a cause of bad MPG..
Any advice/other things to check would be very greatful. You guys have been a huge help so far. Thanks again

Problems with car-
Tranny slips when going up hills in OD-need to change fluid, not related
Car will die sometimes at a stop sign or when rolling down a small hill in town and hitting brakes-could be related
Car seems to struggle to keep speed sometimes, mainly in town at say 30 mph..seems sluggish
Has stock dual exhaust, but barely any comes out the drivers side..blocked exhaust causing some problems? Could the cat also be bad at 124k? post cat o2 sensor?
Could a cracked plug boot cause any of the problems? One was missing a tiny piece on the bottom when I did the plugs, didnt think anything of it.

[Matt95GT]

Start with ignition...
spark plugs (age, proper gap, brand - use stock AC Delco platinum plugs only, other brands will cause problems)
coil housing - check for signs of arcing or cracks
check plug boots for deterioration
bad connections to IDI module, crank position sensor, etc
After that, coils and IDI module would need to be tested.

Yes, the cat could be clogged too... especially if the engine was misfiring or running rich.

[rixGAphx]

IMO your cat prolly IS at least partially clogged.
I don't see haw that would affect the distribution of exhaust through the dual mufflers, however.
But mufflers themselves fail, and can become clogged internally similar to how a cat can clog.

And a slipping tranny WILL cause poor gas milage.

[Nickleahy23]

Start with ignition...
spark plugs (age, proper gap, brand - use stock AC Delco platinum plugs only, other brands will cause problems)
coil housing - check for signs of arcing or cracks
check plug boots for deterioration
bad connections to IDI module, crank position sensor, etc
After that, coils and IDI module would need to be tested.

Yes, the cat could be clogged too... especially if the engine was misfiring or running rich.

The plugs are only a few weeks old and they were gapped to the proper specs. One coil housing was cracked, but at the very bottom and about the size of a BB..Ill look into that one. Plug boots looked alright. I checked all the connectors that I could to make sure they were clean and plugged in tight..

Is there anyway to check for a clogged cat? ive always just gotten rid of them on my trucks lol..The tranny only slips once and a while on big inclines on long distances..That is probably less twice a week..