Alright,
I replaced the fuel pump, fuel pressure sensor and knock sensors (with fresh intake gaskets).
now it still runs like **** and still has reduced performance warning.

I am getting P0300-p0308 p1427 (not sure if that is right precat drivers side O2) and the killing the cat P code.
Smoke tested the intake. No vacuum leaks.
Sprayed everywhere under the hood with ether and brake cleaner just in case the smoke test missed a small leak. Still no love. Verified everything I disturbed during the repairs are correctly attached.

Seen several random misfire threads. most never show the fix.
anyone have any ideas for me to proceed on? I have done what I can think of.

Oh. I did not hit the pressure sensor vacuum hose with anything. I'll check that out next but after that i cant think of where to go from there.

 

Well, what do the fuel trims show? LTFTs, idle & 2500rpm, parked.

Do they show a leak?

Next, do the freeze frame data show a leak or dubious trims?

 

Can you say why you replaced all those things?
Knock sensors almost never fail and have a specific code for each one if they do have a problem. You do not have any codes for the knock sensors?

The code shows misfires on all cylinders which is rare but usually all related to one problem.

The P1427 code points to a problem with the MAF which would affect all 8 cylinders.

I would back up and stop replacing things and do some troubleshooting first.
Do you have the JTIS? It's free on this site and is the factory shop manual.
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Thanks, I'll look at the maf.
search for my other posts it will show most of the codes i fixed....

 

I agree with tbird6

Gus
www.jagrepair.com

 

Disconnecting the Maf made it run worse. Cleaning it didn't do anything.

 

Ok got the software hooked up in the laptop (consolidating the automotive diagnostics to 1 laptop...)

fuel trims stayed at 0% didn't stray at all. that seems a bit weird to me.

P0300 Multiple cylinder misfires
P1000 OBD not ready
P1313 Bank 1 Catalyst
P1314 Bank 2 Catalyst
P1316 Injector system
P1647 Upstream drivers side O2 sensor

Once it cools down I am going to verify all connection under the hood are tight again.
Engine ran fine before I removed the intake manifold to replace the knock sensors. This leads me to believe a short of some sort in the injector wiring.

Amazingly enough though the P1254 hasn't come back since i disassembled the throttle position sensor and cleaned it up.

 

I do not know what year car you have but this list should help identify the proper meaning for your codes.

Link http://jagrepair.com/DTCforms/X103_P_DTC_OBDII_R1.pdf

 

If the O2 sensor doesn't work how can you expect the trims to be meaningful?

 

First time looking at fuel trims. how in the hell am I supposed to know WTF they mean?
I am more concerned with the P1316 code than the P1647 code.

 

I'd swap the sensor now.

If all else fails there are articles online about how cars built in about the last 30 years work.