Acceleration issue

1991 grand Prix 3.4L duel o\h cam 95000 mi
Acceleration issue: car idles good runs good if you drive like little old lady, but if you try to push gas peddle down more than 1\3 to 1\2 way it loses power. It makes no difference what speed, gear, or rpm. With Snap On scanner hooked up you can see timing drop at same time power loss happens. Car has new,TPS & MAP, IAC meters good. ECM has no codes.

Try some higher octane fuel and see what happens. It is possible that the ECM is reading a large amount of knock and is retarding the timing accordingly. I would also check to see if the knock sensor is bad and probably replace it anyway it could be sending false knock readings to the ECM. Finally, check and make sure you are getting good flow through the exhaust. Could be causing too much back pressure due to a clogged cat.

I'll give your suggestions a try in the morning, will let you know if it helps. Thanks for the reply....