Car started running rich and miss firing

[Darkness]

So the other day I took the car out at night for some go fast action with a few of my friends.

After running it hard for several minutes the car started running rough (as if it had a bad tune) and miss-firing. Also noted that the WB was showing about 10-11 AFR when it normally runs at about 15-16 at cruise with low load.

So now the car runs rough a very choppy and too rich. Every now and then I see that it smooths out a bit for a few seconds but still at a 12-13 AFR, then it goes back to running rough. I noticed at high loads and WOT seems to run good.

What could've happened? O2 sensor got burn in the highspeed run? Vac leak, headgasket?

What can I log to see whats going on, it has no trouble codes.

Thanks in advance.

[SSpdDmon]

You can scan and see if it's the O2's. If nothing turns up, check the plugs and wires. It might not be getting a spark somewhere.

[Darkness]

You can scan and see if it's the O2's. If nothing turns up, check the plugs and wires. It might not be getting a spark somewhere.

Funny thing, I reset the PCM and now it runs real smooth but the AFR is still too rich!

[joecar]

Connect fuel pressure gauge to fuel rail;
Start engine, and check pressure, if it's too high, then regulator maybe stuck;
Turn off engine and watch pressure... it it's dropping then you may have leaky injectors which will cause running rich.

Check for restriction/obstruction/debris in air filter and/or air tract.

Check TPS correct range (0..100%) using scan tool.
Check ECT and IAT for correct temps using scan tool.

Check that the front NBO2 sensors switch at part throttle using scan tool.

Check for good spark (plugs/wires like SSpdDmon said).

Check all grounds including battery ground connection.

Some other things.

[Darkness]

Connect fuel pressure gauge to fuel rail;
Start engine, and check pressure, if it's too high, then regulator maybe stuck;
Turn off engine and watch pressure... it it's dropping then you may have leaky injectors which will cause running rich.

Check for restriction/obstruction/debris in air filter and/or air tract.

Check TPS correct range (0..100%) using scan tool.
Check ECT and IAT for correct temps using scan tool.

Check that the front NBO2 sensors switch at part throttle using scan tool.

Check for good spark (plugs/wires like SSpdDmon said).

Check all grounds including battery ground connection.

Some other things.

Hmmm sounds like a good idea to check the fuel pressure. I'll check that out tomorrow and will let you know. Thanks.

[Darkness]

Nope, all looks good, still doing it though. What could it be?

[SSpdDmon]

Might wanna pull the valve covers and take a peak inside then.

[Darkness]

Ok this issue is getting too old already. What should I log to see what going on? I pulled the valve covers already and everything looks good.

[TAQuickness]

have you replaced your O2's yet?

[Darkness]

have you replaced your O2's yet?

No, should I? Cant I just log them to see if they're working properly?