Misfire on Cylinders 5, 7, 8 (FIXED! Broken Valve Spring)

[PAFirefighter11]

Slight Update: When I unplugged the MAF the misfire code and blinking CEL disappeared. It still has a misfire, but nowhere near as bad. I tried installing a used MAF out of a working vehicle. Plugged it in and the CEL blinking, misfire code, and horrible drive-ability came right back.

I've been posting on my Trans Am / LS1 specific forums and so far no luck. So, I figured I'd post here for the hell of it.

This is on my '98 Trans Am. On July 25th, 2012 I was driving in to work and I noticed some hesitation in 6th gear at 65 MPH. Wasn't a big deal I thought. Then, I noticed it at lower gear, and now while accelerating in every gear. It's like a full auto AK-47, for example, in terms of rate (not loudness). It idled fine.

My SES light has been on for a year now now. It's telling me the driver side cat is bad. On my drive to/from the Hamptons (On the weekend prior to 7/25/12) I hit 2389048923480234 bumps, pot holes, etc., mainly on the Belt Parkway & Staten Island Expressway. Is it possible it rattled my cat apart and is now clogged up?

Fast forward to a couple weeks ago. Things are MUCH, much worse. Car won't idle properly. Can barely drive it. It's missing BAD. Above 35 MPH the CEL blinks, which as we all know is not a good thing. Here is are two crappy videos to demonstrate what's happening (at idle at least):
http://www.youtube.com/watch?v=_n_8yLhQNtU

http://www.youtube.com/watch?v=4sOfqrMLJlc


2 weeks ago I drove the car to a guy on Yellow Bullet. He is an engine builder and has done several LS1 and other cars over the years. He hooked it up to a SnapOn scanner to monitor the car while running. I think it's the SnapOn Solus. Hooked up fine while the car was off. Then when the car was running it had several issues trying to connect. Finally it worked and we got this...

-Cyl #5 misfire
-Cyl #7 misfire
-Random Cyl #8 misfire
-Random Cyl #6 half fire

CEL is on. Codes are only showing P0420 (Catalyst efficiency below threshold on bank 1). However, o2 sensors are reading as normal. Cat temps are running within normal ranges as well (Checked with an infrared thermometer). Other code is "Cylinder misfire detected".

Other issues:

-Third brake light sometimes illuminates like a rear tail light. On while lights are on, then brighter when the brakes are applied. I have an LED 3rd brake light installed btw.
-Turn signals are also acting weird. They blink quickly, slowly, normal, and anything between.

I changed the plugs to NGK TR-55 plugs. Wires are brand new as well from Vengeance Racing. We have checked the injectors & coils. Used some from other working vehicles and they did not change anything. They are fine. Also got a noid light on the injector wiring harness. Checked fuel pressure and it's good, in the green at 55 psi. So I am thinking harness or computer? I am borrowing a computer from my buddy who removed it from a '98 Camaro SS.

2 interesting things. First, I just noticided this on the ECU I pulled from my car is a reman:


Second here's the corrosion that's all over both the ECU and the harness side (I cleaned this all up since the photo):


Also figuring maybe grounds? I removed the 4 easily accessible grounds: Driver side strut tower, driver side front next to the intake, passenger side strut tower, passenger side front next to the intake. I filed down the grounds metal contacts and wire brushed them as well.

Started up the car and it ran basically 99%! I took it for a 0.5 mile drive and it slowly got worse. At stops it would almost stall. I brought it back and parked it. It seemed to get worse the longer it was running. However, overall it seems much quieter and seems to run much smoother as well (This is with the other ECU).

Should I just replace the driver side cat and see if that fixes things?

I REALLY want to be able to enjoy my car again, but I haven't been able to drive it in months 'cause of this crap. Thanks!