Cannot solve this issue: hesitation at anything more than part throttle

My car hesitates badly at more than 1/4 - 1/2 throttle.

Ok, so I have searched about every keyword I can think of on this forum and others. I can't solve this issue. My car has 89,000 miles on it, still original speed density.

It's worse when cold, but even after the car warms up it hesitates BADLY at tip in throttle.

If it's cold and I am in a hurry I will usually get a intake POP or backfire when I try to go WOT after shifting into 2nd gear.

Starting off from a dead stop, if I try to burn the tires and mash the gas pedal and let out the clutch quickly the car just falls on it's face. And this is with 3.73s! If I use like 1/4 throttle or so and slip the clutch it goes much better.

Shifting from 1 to 2nd, if I try to do it quickly and go WOT immediately after shift, it stumbles and hesitates badly for about half a second, then continues on ok.

If I give it gas like a grandma and use like 1/4 throttle or so between shifts and when taking off from a stop it does ok, just pud slow.

It seems to me much worse at low RPMS, on the highway at speed it's much less noticeable but still there.

I have a DIGITAL OBD1 code reader and the only codes I got were something about the A/C and the "system ok" code I think it was 11.

I have replaced:

Plugs with Autolite ones, properly gapped (old plugs looked good)

Plugwires with Ford Racing 9mm ones.

Cap and rotor with Motorcraft ones.

Fuel filter with Purilator Gold one.

Checked timing with timing light with spout out (was at 10deg, now at 12deg)

TPS adjusted to .98

Replaced air filter with new OEM one, now currently running a new MAC CAI that I got cheap on Ebay.

Ran a can of fuel injector cleaner in the last tank of gas.

I just put the Magnaflow catted H on, so the cats are brand new. The smog hole on the H is blocked off.

Smog pump delete pulley is on the car and openings in the back of the heads have bolts in them with sealant.

Where do I look next guys?

Does this sound like a :

vacuum leak? (I checked the hoses and couldn't find a leak)

bad injector?

bad fuel pump?

Any ideas are really appreciated guys. I am out of ideas.

EDIT *This is not a new problem, it's been like this since I bought it a few months ago, I was hoping it just needed a tune up, but I guess not.*

Thanks

I seriously do apprecaite the response, but I don't have one.

Thanks

Thank you for the input about those sensors.

In all the threads I had read I had no idea the TPS could be bad and still adjust within spec.

I will start on your suggestions.

Thanks again, atleast now I have some things to try.