'00 Burban rough running....

[azmotorhead]

Starting to diagnose my neighbors 00 burban with a 5.7.

current status is Starts & idles fine but when brake torqued or placed under a load the engine will start to missfire at 1500rpm.

No trouble codes pending or set, O2 sensors reading what they should, MAF cleaned.

These things have any inherent flaws?? This is the first Gen III Small block I've worked on.

My curent plan is pull And inspect plugs & check High tension leads.

Any tips are greatly appreciated

[tahoe33]

I had the same problem with my 1995 Tahoe, The dealer had the truck for a week and change the coil, distributer, and egr valve .I did a full tune up, they check the cat. and could not find the problem. Lucky I know the service manager and they only charge me for 3 hours labor and egr valve. I change the cat convertor and the truck mileage went from 13 mpg to 15.5 mpg around town and 17.5 on the hiway. the truck has on 65,000 miles.