Ford Repair: engine pinging, throttle position sensor, mass air flow

Question
I have a 1994 mustang gt with the 5.0 engine and automatic transmission.  I have retrieved codes 181 and 189 from the computer.  Also, from a dead stop the car accelerates fine, cruises on the highway fine, but under medium acceleration(such as going up a hill) there is a lot of pinging from the engine.  At full throttle the car seems to accelerate fine.  I have had the car long, so I don't know what it ran like when it was new.  Can you help?

Answer
Hello and thanks for the question...I'll try to help.
 It seems that the engine is running at a rich adaptive limit, indicated by the fault codes you got. I would check a few things:
1: voltage at the TPS (throttle position sensor)
2: voltage at the MAF/MAP (Mass Air Flow/Manifold Absolute Pressure) sensors.
3: basic tune up condition of the engine
4: EGR system
5: Ignition timing
6: Check for engine vac. leaks
Hope this helps,
Erik