If you hit the same rpm without spining the tires, does it still stall?

Might want to check fuel pressure while someone smashes the throttle down.

Is your air cleaner clogged?

 

No it seems to be only when the tires spin. I will have to see about testing the fuel pressure but it runs great in any other conditions. Air filter is a little dirty but not plugged and the vacuum indicator is not tripping.

 

I remember a post of a guy snowplowing, having a similar problem, the engine would stall when pushing a load of snow...

 

The PCM will reduce fueling at 4000 rpm's, but sounds like there is something else going on.