502 Idling/throttle-up Issue
 

I have a 1995 - 502 EFI that when its in gear at idling rpm for a couple minutes, the motor starts to run rough and will not accept any further throttle whether you pump it or try to ease into it. In fact, when you do either the motor will stall. IF, I keep the RPM at 900 or so this issue does not occur. At 900 RPM up to 4800 rpm the motor runs without issue!

Below lists all that has been done or tried thus far:

1.) High pressure fuel pump replaced. (It was so hot you couldn't keep your hand on it..thought it might be vaporziing the fue - no such luck!)
2.) MAP sensor replaced
3.) IAC sensor replaced
4.) Low pressure & high pressure fuel pumps are both operating within their specified pressure range.

HELP!!!!!!!!!!

Come on guys, someone has to have had this problem or know how's to solve it.........