I have checked everything there is to check and it doesn’t throw any codes. Everything fuel, air and spark related. It just doesn’t want to accelerate sometimes and if you try to just give it more gas it starts dropping rpm and backfiring almost like it’s getting the fuel but not the air or something is putting a huge load on the engine not letting it rev. Sometimes it drives just fine and randomly at the next stop light it’ll just decide it doesn’t want to accelerate and I have to sit there off and on with the throttle until it wants to go
I'm a DIY myself but go to my local mechanic if i can't pinpoint the problem.
It could be anything from bad/clogged sensor(s), worn clutch, clogged fuel or air filters, TCU/TCM, ECU/ECM, low fluid, engine, ignition, etc.
EDIT: looks like you checked or replaced alot of components already. I'd just take it to your local mechanic and let him pinpoint it. Will be $50-100 well spent. Also, did you test your MAF with a VM/DMM ? you replaced the O2's but the MAF is 18 years old? You sure it's still good? Last time fuel filter changed?
Like Edmaz said above, try your diagnostics first...
Or just take it to your local garage and see if they can pinpoint the problem.
My process is try to diagnose the problem and then fix if easy. If can't locate the problem, then take to my mechanic. If he determines it's something complex or I'm too busy at work, i just let him fix it. Otherwise, i just fix at home.
Any lack of acceleration problems I've had on other vehicles was due to bad/defective/clogged sensors or a bad ECM/TCM. Refurbished EMC/TCM worked fine.
But I always properly maintained my vehicles.
If you're not the first owner or if the vehicle wasn't properly maintained and driven, could be clutch, fluid, filters, ignition, etc.