2003 Suburban Power Problem
 

I have been working on this problem for a few weeks. 03 Suburban approx 140k miles, 1500 4x4, 5.3 flex fuel. When trying to accelerate it just boggs down and misfires. I have done the following.

1. Code indicated bad MAF, replaced,no change. Also unplugged it to see if default would change situation but did not.
2. Purchased fuel pressure gauge, 42 psi at fuel rail.
3. Disconnect fuel regulator vacumn and it goes up to about 50 psi, suppose to indicate a good regulator.
4. Replaced fuel filter canister on frame.
5. Pressure read 42 psi after filter change.
6. Dropped tank and installed new fuel pump module, still 42 psi and no change in performance.
7. Purchased infra red thermometer to read exhaust system temps. Ran car for ten minutes and while at idle temp read about 300 -350degrees F across both cat converters. The only extreme hot spot was the elbow coming off the driver side exhaust just after the cat converter. The elbow area had a 450 degree reading. It seems logical because of the 90 degree turn it has to make and will retain heat. This higher temp occurres in a small 2 inch area. 350 at the cat conv,450 at the elbow then back to 350 along crossover pipe t0 other cat conv. I tested with engine running for about 30 minutes. My guess is the cats are ok but not certain.

Any help would be greatly appreciated. Thanks

Well the problem was the cat converter. The driver side cat totally plugged. I ordered an Eastern Cat Converter. It was a perfect fit for $325 and free shipping. It comes in two parts that connect at crossover which helps with install. You still have to drop trans cross over support to get it in but fairly simple. Loved the sound coming straight out of headers. Anyway, no codes and running great.