Update: after more online research I pinpointed the problem to a broken intake valve spring on cylinder #5. Thankfully the spring was intact so no metal shards were causing engine damage and it kept the valve from contacting the piston. It was a very simple repair and only $7 for the spring. Make sure the cylinder is DTC so the valve cannot fall down into it or, like I did, pressurize the cylinder with an air compressor to hold the valve up. Pop the valve cover off, take the 8mm rocker bolt out then push the spring cap down to remove the keepers and the spring lifts out. You do need a valve spring compression tool to install the new spring; auto parts stores will rent it to you or Harbor Freight for a cheap one. She runs like a champ once again.

My 2005 Suburban (203k miles) left my wife sitting along the highway last week. She was using cruise control and said it felt like something was braking the vehicle, I'm assuming it was getting bogged down. She kept driving it off cruise and got into a parking lot and couldn't get it to start.

I recovered the vehicle a couple days ago by driving it home with constant throttle. The CE light was flashing the whole time. It will start if you press the throttle a good third of the way in but as soon as you let off it dies.

The codes it kicked were:
p0300 (multiple cylinder random misfire)
p0449 (evap emissions control malf)
p0101 (MAF or VAF circuit)

I unplugged the MAF and there was no change.
I thought the cats were plugged up based on the way it drove and a couple people online saying they had the same issue. The next day I dropped the Y pipe and it started right up, I let it idle for about 30 seconds and shut it off. It seemed fine. I ordered an aftermarket Y pipe with cats and installed today and it wouldn't start without throttle. I unplugged the upstream o2 sensors based on some online reading and no change.
I disconnected the evap line from the solenoid by the throttle body and tried to blow into it to check if it was stuck open, it was not.
Fuel pressure on the rail was around 52 PSI when I turned the key and a little over 60 when I got it started. The needle moved some when it was running but not drastically (a few PSI).

Now the codes shown are:
p0300
p0449
No MAF code.

A little background on the truck, it has had some electrical issue for awhile that drains the battery when left sitting for a couple days. Also the heat/ac blower motor runs constantly so I pulled the relay for it. I'm starting to wonder if the vehicle is going brain dead. The wife had the alternator and battery replaced the week before all this happened.

Thoughts?

 

evap code is for the canister vent valve...the valve is probably stuck...shouldn't cause an issue cruising. worse case a blocked evap vent line could collapse the tank as air can't enter as fuel is pumped to the engine. if it was blocked you would have a slow refueling problem.

the misfire condition will cause the flashing mil and will cause serious drivability problems. you need to identify which cylinders are misfireing. Chevy has misfire counters in the obd II monitor section so use the scan tool to see live and history misfire data. Knowing what cylinders are accumulating misfires leads to the next step of diagnosis.

if the maf dtc resets...address it then.