It will idle a bit rough but will not run over 5 to 10 mph.

No check engine light and ALL sensor read good! I have heard some talk of the "Power Reduction" light or button cause similiar problems....but, I really don't know what to try next.

Have a mechanic to unbolt the cat converter see if it makes a difference Something is clogged on your exhaust system

Have already done that. The converter is not clogged.

Okay do a compression test each cylinder then

Already tested, all cylinders good

What's the psi?

Not sure. My mechanic did it last week....said all where good. Only has 112,000 miles on it. Enigine was in great shape when I purchased it a few months ago. My mechanic checked it out before I purchased it. So far, we have ruled out, blown gaskets, converter, TPS sensor, cracked block....etc.

What about do a fuel pressure test?

Dropped tank, blew out the fuel lines, replace fuel filters and verified fuel pump pressure. Lmao....been there....done that. I'm at an impasse.