Hi everyone, I apologize if this is in the wrong place(still sorta new to the forum). Here's my problem

A few weeks ago I was driving for a good hour or so with everything running "well" on my rebuild, with about 550ish miles so far, when out of nowhere, it seemed like my fuel became too rich out of nowhere. I was already running rich to start with, but it changed to if I have more than like a quarter pedal throttle, the car lags like crazy and, with enough throttle, will back fire a lot. I got my codes checked, and ended up having to change my map sensor, which didn't solve anything. I changed my plugs, and it seemed to work better for about a minute, and then went back to the same problem. The last plugs were all fouled, which didn't surprise me too much, but I'm just confused of why this just happened randomly, without changing any settings on my MS.
After this started I tried messing with the fuel a little, but I'm super afraid of messing up the engine, so I didn't change much besides the fuel pressure at idle mostly.
Could this just be a tuning issue? Maybe a sensor or a connection went bad on the MS wires? Should I just turn down the fuel pressure on my afpr?

Here's my setup:
97 talon, 2.0L 420a, Wiseco pistons, Eagle rods
Wally 255 pump, accel 490cc injectors, 1:1 afpr
manley valve springs and valves
Hahn S16g turbo (no boost as of now for break in), HKS ssqv BOV
MS2extra with mostly default settings until I find a tuner.

thanks in advance for any help!

Interesting.

Do you have a log of the engine running?

Too much fuel will lag a lot.

How did you change "fuel pressure at idle"?

What are you using for your fuel system / regulator?

I'll have to get the log next time I have a chance to get to the car. For the idle thing, I richened up the VE table at 600 rpm so it wouldn't keep trying to die on me...might have been a mistake.
For my fuel system I've got a wally 255 and an aeromotive 1:1 afpr.

I've tried leaning out the mix a little, but I'm really afraid of making the car blow up on me. I'm like less than a novice with this stuff.

What are your AFR's at idle?

Also, if you have a pretty normal setup as far as injectors go, keep your fuel pressure at idle in the low to mid 40s. Turning that screw and lowering fuel pressure across the board is worse than making changes to the fuel table.

Ideally, set fuel pressure at idle to what your injectors are rated for, quite possibly 43.5 but I'm not sure on your exact ones. Then, be sure your Req Fuel value in megasquirt is correct. Then, leave reqfuel and the fuel pressure reg alone and worry about your fuel table.

Check AFR if you can (hopefully you have a wideband on this sort of setup, it is near-essential). There are other methods, but for the money you can't go wrong, especially on a motor you have some money tied up in.

The good news is that if you blow it up I'll buy your valve train