98 mustang randomly loses power

I got a 98 v6 a couple months ago and when I got it, the fuel pump went out. I replaced it and kept the stock gasket because it looked fine (and I just wanted to drive it already). It runs decently now, but sometimes the car would lose power, like it went into some kind of limp mode or cylinders weren't firing. Out of the many codes the car has, the P1443 is what I think is causing it. I've heard a solenoid valve stuck open could cause a vacuum leak so I'm wondering if it's that, but so can a bad f-pump gasket. I've left the code alone for a couple weeks and it was fine until yesterday when the car had lost so much power I could barely get out of first gear. I had to pull over and wait a minute or two, then it gained a little more power back until it was back to normal again. It also lurches when it's being driven while low on power.

I was also low on coolant as I have a leak, but I doubt that was the cause. Thanks for anyone who can help out and offer advice.

P1443 shouldn't have any affect on power. It is simply for the evap purge solenoid which just dumps gas fumes into the charcoal canister.

A bad fuel pump gasket will likely not even let the car start because the pump can't properly prime.

You stated you have numerous codes. Maybe you should list them all and maybe we can get you pointed in the right direction.

P1443 shouldn't have any affect on power. It is simply for the evap purge solenoid which just dumps gas fumes into the charcoal canister.

A bad fuel pump gasket will likely not even let the car start because the pump can't properly prime.

You stated you have numerous codes. Maybe you should list them all and maybe we can get you pointed in the right direction.

The codes are as follows: p1443 (thrown twice), p1131 & 1151, p1000, and p1260 (thrown twice). I also noticed another thing today. The car normally idles a few hundred rpms below 1000, but when it loses power it will idle at 500 rpms.

Regarding the lean codes, the bolts keeping the passenger side headers and exhaust system connected seem to have slipped a bit as the gap between them seems a bit too large, but I've never seen another 98 mustang's header connections so I can't be sure. I don't even know if the computer would make it run so poorly if it thought it was lean but might be good info.