96 cobra running rough at WOT in lower RPM range

[Abneriel]

It started running a touch rougher than usual about a month ago, so I did the usual maintenance: oil change, fuel filter change, cleaned out the K&N...then the other day it started running really poorly at WOT in the lower part of the RPM range. It seems to do alright after 3.5k or so, but if I throw the gas pedal down at 2k RPM the car starts sputtering pretty badly and the acceleration is really choppy. I'm pretty sure I've heard a couple of mild backfires, but no gunshot loud ones. I was assuming it was ignition related and have changed out the plugs/wires but still need to do the coil packs, etc. No change in the issue after the plugs/wires were replaced.

Anyone have any suggestions? The car seems to run decently from 3.5-6k (didn't take it all the way to 7k) but REALLY suffers down low when the gas is applied. The idle is a touch rough, but steady, and is at 910ish or so instead of the usual 850.

There are no mods to the engine itself. Just some gearing and weight reduction/brake upgrades.

 

[94svtford]

make sure all your vacuum lines are connected and no cracks in them, clean out your egr valve with some brake clean, make sure u have right gap on your plugs, also dont over oil your air filter, if you have a tamper bit take your maf out and check the wires and see if theres any crud on them, if there is grab some of that crc mass air flow sensor cleaner. Also make sure you put your air intake on right and have no leaks anywhere

 

[Abneriel]

make sure all your vacuum lines are connected and no cracks in them, clean out your egr valve with some brake clean, make sure u have right gap on your plugs, also dont over oil your air filter, if you have a tamper bit take your maf out and check the wires and see if theres any crud on them, if there is grab some of that crc mass air flow sensor cleaner. Also make sure you put your air intake on right and have no leaks anywhere

those are all fine, we checked all of that because of the symptoms and it didn't change them...we DO still need to go over the vaccuum lines, but I'm starting to wonder if it isn't something more serious as it became worse on a test drive last night.