Help please

[mandott]

Hi I’m new here, just made an account because I cannot figure this issue by myself. I have a 2003 tahoe LS with the 5.3 FLEX FUEL. It wasnt in the best condition but ran a good 10k miles before it crapped itself. The original issue was that it broke down on the highway and when i tried turning it back on it idled really bad and smelled bad. While I was looking for potential issues I noticed lotsss of oil leaks.
At home here I did a couple fixes: new valley pan gasket, new knock sensors and harness, new intake manifold gaskets, new valve covers + gaskets, new vacuum lines.
I’ve swapped new parts from autozone onto it such as a MAP sensor and the Mass Air Flow. Still no difference. I checked the purge valve and its fine.
I ran the OBD scanner and got 4 codes. P0101 (Mass Air Flow sensor performance), P0102 (Mass Air Flow sensor circuit low frequency), P0106 (Manifold Absolute Pressure sensor performance), and P0300 (Engine misfire detected).
I am going to check the voltage of the map sensor, the MAF sensor due to live readings was reading about 30 g/s during acceleration.
I couldn’t read the idle data due it not wanting to stay at idle, it cranks for like 5 seconds fires up and then dies. If you guys can recommend anything please let me know.

 

[Scottydoggs]

aftermarket mafs kinda suck in general. so that maybe the issue. might be a blown fuse under the hood, marked ING. or the wires to the plug to the maf are dry rotted and cracked and showing bare wires. used oem mafs off ebay have a better chance at working right.

 

[NoReverseYukon]

The bad smell to me indicated that your catalytic converters are clogged. The misfires & MAF/MAP dumping so much raw fuel into the exhaust causes this.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

I'm sorry, but I've read your post a couple of times, and I'm struggling to understand your core issue. Is the core issue that the truck starts, but only runs for a few seconds before it dies?

 

[PNWYukon]

Massive vacuum leak. If it won't run for more than 5 seconds, then check fuel delivery. If the cats are clogged it should still idle, albeit roughly.