We have had many lazy lifters that took a few seconds to fill but worked perfectly at redline.
The black plug could be from oil. A leaking valve stem seal? Could be from a poor firing plug as well. That's your biggest clue thus far.

Hey Jason,

Does the car run fine when dead cold, or for about 30 seconds when warm?

I went through this exact thing and all the machinations you've gone thru. The good news is I didn't have to pull the head to fix a broken valve spring. I also got new plugs, wires, cap and rotor plus rebuilt injectors, all to no avail.

I ended up replacing the AFM but that made it worse. Still thought it was the AFM so I drove to picknpull in San jose to get one and got another from Steve. It took a few tries but one of those was good and problem solved. I did have to change the DME also for some reason because it would surge at idle but run fine off idle.

The point is mine would run fine on the warmup/startup circuit but once off that the trouble would start.

I will see at Steves Saturday and if I get a chance I'll pull my afm & DME and loan them to you. I do have a Christmas party tonight and tomorrow so don't know if I'll get the chance.

I sent my injectors to Marren in Ct and would recommend them. Quick turnaround and quality work.

I also have a lazy lifter that ticks like crazy until I take the car on track. Usually it stays pumped up for the season if I start the car at least once a month but sometimes I'll race Saturday and it will be noisy subdY morning.

It runs "OK" (but not perfect) for about 10mins, but then just loses all power and starts missing like crazy (like in the first video). At that point it just had no guts and does not accelerate.

Thanks for the recommendation on Marren (www.injector.com).

Don't know about anything on Saturday, so don't rush, I will grab them another time. I have lots of other things to try for now and will do the bench tests of everything electrical. That will hopefully find something.

I've had AFMs do all kinds of weird stuff. One case was almost exactly what you are describing. They are super easy to change. You can try the one off my car which appears undamaged.

I wouldn't read too much into spark plugs unless something was REALLY obviously different (like soaked in oil etc).

I use Witchhunter www.witchhunter.com/ for fuel injectors. I've been really impressed with them and they're close by (WA) for a quick turn. They've called me when I had a bad injector, I sent a replacement, and they still just charge the one fee.