BlacktalonAWD

I recently rebuilt one of my 502 efi's gen 6, after overheating it badly and wasting the mains, after putting it back in, at first I couldnt get it to go past 2700-2800 rpm without loosing power if you went past that RPM it would drop down (like it was running out of fuel), then after 30 or so seconds it would come back on and you could go to 2700-2800 rpms as long as you want, just as long as you dont go past that. we put it on a scanner and everything seems fine, we disconnected the temp switch and now it will go to 3400rpm and no further. the other engine runs perfectly fine, and previous to the rebuild it would run 5000rpm.

Would a bad coolant temp sensor cause these problems? oil pressure switch? any ideas?