Engine Code 124, 176, 177, 543

[FullerMTU]

I have a 94 Explorer XLT that has been giving me problems. Whenever I drive a longer period of time on the highway (70-80mph), the CEL comes on along with loss of power. It will come on and then go off and so on. The motor also pings.

I scaned the computer and these are the codes that I came up with.

124: Throttle Position Sensor voltage higher then expected
176: Heated oxygen sensor indicates lean condition, left side
177: Heated oxygen sensor indicates rich condition, left side
543: Fuel pump circuit open, Battery to PCM

I have replaced the o2 sensor, cleaned MAF, and re-torqued the intake bolts. Are these are these codes all related to the same problem, or are they seperate? Anyone have an idea as to what is causing this?
Thanks

 

[MrShorty]

By the book, you diagnose and resolve the lowest numbered code (124), clear the codes and see if the others come back. I don't have the pinpoint tests in front of me (usually go to the library), but I would suggest you figure out why you're TPS voltage is too high and go from there.

 

[FullerMTU]

I guess I should have said this in the begining. The 176 and 177 keeps coming back after I reset the computer.

 

[MrShorty]

So the 124 has gone away and you're still getting the 176 and 177? Since you've already replaced the O2 sensors (assuming you didn't get duds; it has happened before), how are the wiring and connections? grounds for the PCM?
Ford publishes what are called pinpoint tests for each code that you can usually look up in a good manual. They take you systematically through the possible causes for each code and help you track down the real cause. If you don't see anything obvious in the wiring or connections, it may be worth a trip to the library to look up the pinpoint tests.
Do you know anyone who has access to a good scanner? (not a code reader, but something that will allow you to monitor sensor output). From there you can monitor what the computer sees from the sensor while forcing it to go lean or rich.