Hello all! Been having an issue with my 03 suburban and I'm hoping for some guidance.

The problem is anytime I get more than about half way down on the gas pedal it the engine starts cutting out/spitting and sputtering.

The car has had an electrical issue since I bought it earlier this year where the dash would blink off start dinging and the door locks to cycle. I read somewhere about a bad ground in the back of the engine and sure enough that connection was bad. I got that wired up but didn't help the intermittent dash/door lock issue.

I moved past the electrical issue and then I started having the engine performance issue.

So far I have changed the coils, wires, plugs, fuel filter, and fuel pump. I also thought maybe the cats were plugged up so I unbolted them for a test drive, no such luck. I have a knock sensor code and O2 codes which have been set since purchasing the vehicle. I thought it could be a throttle position sensor but the sensor reads a smooth graph when testing it with the engine off and running/driving.

Any insight would be appreciated!

2003 Chevy suburban 282,000 miles 5.3l flex