Guy I need your help!

[Mr.Cornelius]

01 GMC 4.8
161,000 miles
Premium always

OK guys, I was coming home from a 120 round mile trip and the truck was running great. About 10 miles from the house I started to feel the truck hesitate and then BAM! Dead miss. SES light flashing consistently kinda slow, lost ALL power and backfiring and popping. It was around 2am and I couldn't call anyone to come and pick me up so I made the decision to "limp" the truck home.(yea I know not a good call) the truck then started to down shift and up-shift like crazy. It wouldn't hardly pull itself in second gear about 3200 RPMs. made it all but 2 miles from the house when the truck just dies. I coast in to a parkinglot and hit the key, and it barely would turn over like a dead battery (I own an automotive electrical shop and I built a 2.2hp OSGR starter for it and have a Deka 1450cca battery and 340amp alt on it, all are good) It was just so damn hard for the starter to turn the motor over. I walked home. Later the next day I got a ride so I could go and check out the truck. Hit the key and it started even tho it wasn't happy about it lol. when it started EVERY valve and lifter sound like they are knocking for a min then it clears up ALMOST. Still has a dead miss and is blowing what looks like a mix of white smoke and water vapor out of the dipstick. Knocking that I pulled the PCV valve to see if it was clogged while running and after about 1.1 seconds after pulling it out, I cant see anything under the hood of my truck it was so covered in this "Fog". IDK what to do next, any suggestions or anyone know what this might mean? Is it time for a 6.0 already? Please any help will be greatly appreciated. BTW when I left for Nashville I checked the truck over, spot on oil and water ect. now it over 1qt low on oil

Oh and I got these codes out of it
PO101
PO126
PO300
PO420

[tanz45]

Mass Air Code
Coolant Code
Multiple Misfire Code
Cat Code which could be from the coolant sensor not working as well

Well, a flashing engine light is the worst. Means that you are doing damage to your cats. Dumping all that raw fuel into your engine. Bet if you smell your oil it reeks of gas. So that might explain the noisy lifters.

Sounds like a head gasket too.

[truckinL33]

My first step would be to drain the oil and see what it looks like.

[pl4yboy]

My first step would be to drain the oil and see what it looks like.

My second step would be to pull the heads.

[Mr.Cornelius]

Thanks for the input guys. I finally have a day off tomorrow so I guess im gonna yank the engine down and see what it looks like...if its too much to fix I have a buddy thats got another 4.8 out of his truck he wrecked with only 48,000 miles he said he would sell me for $350. Its complete down to the AC pump

[truckinL33]

for the amount of money it would cost to fix just about anything that could be causing your problems, you're probably better off buying that very low mileage engine anway. Especially seeing as you have 432423789752 miles on your engine.