Well....I am glad I am not crazy (well maybe) I did find a post in the archives, saying the scans will say closed loop at WOT. I will be checking mechanical issues for now, such as the cam and valve lash. This one is for the archives....in my stock 870 bin, there is a setting for the number of cylinders. It was set at "zero" and I changed it to 8. The car ran terrible (very lean I think) and I immediately changed it back to zero. I also unplugged the MAF, and hit the wall hard at 3800 RPM. I am becoming more convinced that my electronics are working fine, and that my problems are base mechanical related.

 

I would go ahead with the new cam install...or at least check your cam timing...if you have skipped a tooth somehow, your high rpm problems are completely explained. IIRC, too little cam timing causes compression to bleed off at high rpm's causing exactly what you are explaining, too much causes no torque on the bottom end. (or vice versa). I have been doing extensive research on L29 big blocks and have found out that GM retarded the cam timing to keep the HP #'s down as to not overshadow the "new" 6.0. With these motors a cam swap using the "marine" cam that advances the intake centerline appx. 4 degrees with 20* more duration, 4* closer lobe separation and no more lift is worth 95HP. Being off by a tooth on the cam sprocket is not enough to make the engine not run but it will not run at its optimum...another thing is many aftermarket cams have 4 or 5* timing advance ground into them. Check with summit to see if there is anything different with the cam you have currently installed...maybe its ignition timing causing the flat top end if your cam is ground with advance in it and you haven't taken that into account.