SR Hesitation/Stumbling problem after new ECU

[96Turbo]

Ugh...I've been trying to avoid making a thread about this but i'm running out of ideas.

bone stock SR20 Blacktop

Previously, the car was running a redtop ECU and everything was fine. Then i got the bright idea of installing a Nistune board on that ECU. I ended up having problems with that because of a few things (wrong base image was sent on the daughterboard, and possibly an installation error), so I tried reverting it back to stock (by changing a jumper on the board). This still didn't fix it as it was running like ass and going into limp mode.

So i figured I fucked up the old ECU and that was it... so i bought a used blacktop ECU. It runs better, but I've got problems I didn't have before I started screwing around with it.

The engine hesitates/stumbles from about 1800-3000 rpm. Pretty much any throttle level. Just cruising around 2500 rpm you can feel the car bucking and if you try getting on the throttle it falls on its face and definitely feels like it's pulling timing.

Code 55 all day, new plugs gapped to .035, MAF is clean, CTS is new, AAC is clean, no visible vacuum leaks....

When i went to set the timing it was kinda sketchy. With the TPS unplugged & idle set around 800rpm it sounds like it's struggling to maintain a steady idle. Also, the timing marks jump around +- a few degrees while I'm trying to set it. Also, after a few minutes of steady idling (tps unplugged) sometimes the idle will jump up to about 1500 for a while (timing marks go crazy, usually goes down to about 0 or +5), and then settle back into the low idle.

Ignition problem? Bad CAS? Fuel pressure? Since the car ran fine before I fucked with my ECU that must be the root of the problem. What could I have messed up by running a faulty ECU that a new one isn't solving?

I would appreciate any help. Thanks!

[96Turbo]

Also, after i set the timing the last time (I've done it like 10 times now i swear), the stumbling has almost gone away. It's much smoother, but definitely not gone.

In all my searching for someone with a similar problem I found a thread about one guy who's CAS was off by 1 tooth or something??

I still think it's gotta be related to running that original redtop ECU that must have been damaged when installing the daughterboard...

[GSXRJJordan]

Mechanical timing could be off... that's the chain that would be off a tooth.

The car otherwise runs strong?

[fliprayzin240sx]

What spark plugs and gap it less.

[96Turbo]

Keep in mind that this thing ran PERFECT before I started fucking with the ECU, so I don't think it's mech. timing.

I've got NGK coppers, stock heat range (6 I think??). But I ran them for a few weeks with a ridiculous gap (~.04") Could I have damaged a coilpack doing that?

And this happens while under light/no load. Doesn't the plug gap usually have more of an effect under boost/load?

[96Turbo]

regapped the plugs to .028", checked MAF reading at idle (~1.7v) which is close but a little higher than spec. I checked the resistance of the TPS which was 11kOhm closed, and about 2.75kOhm wide open. I'm still checking to see if this is correct. - No change

There's a bad pulley or idler (on the AC belt I think) that's making some nasty noises every once in a while. I'm thinking this could be pissing off the knock sensor and making it go limp. So i'm gonna pull the belt, reset ECU, and see if anything changes.