Stop replacing sensors and controls, you are making matters worse.
Each time you change a sensor or control it can take computer(PCM) 1 week to 2 weeks to relearn new parts parameters.
And if you change something else during this time it gets even more confusing for computer.
Buy a Volt/Ohm meter(DVOM), $20-$30, it will save you literally hundreds of dollars
157 Mass Air Flow signal is/was low or grounded
172 Oxygen sensor not switching - system is or was lean
543 Fuel pump monitor circuit shows no power
Are these current codes or have you replaced things since reading these?
The part you replaced on the Rad Support is called the EDIS-6 module, just FYI
It controls the spark(coil pack), it can run on its own or with computer(PCM) assistance.
First the basics
Coil pack wiring:
3 4
2 6
1 5
Front
The 5 6 4 side always gets me, I either reverse wires here or at the spark plugs, check it and then check it again, if you KNOW FOR A FACT it is right then get someone else to check it, lol
Start engine cold, it should idle at 1,100 or higher RPMs, if not PCM is not going into Choke Mode, or IAC Valve needs to be cleaned, NOT REPLACED, I see you did all ready.
A word about sensors and controls(IAC Valve is a control), they rarely fail.
90% of DIY mechanic replaced sensor/control were still good
But 50% of pro mechanic replaced sensors or controls were still good as well, but I think that has some bill padding in it.
After engine is warmed up, temp gauge should be above 1/3 and under 1/2, if not replace thermostat 4.0l should run at 195-200degF, colder costs you money.
Idle should be at 625rpm for manual trans, 750rpm for auto
Unplug the IAC Valve wires.
Idle should drop to 500rpm or engine may even stall, either is good, it means no vacuum leak.
If idle stays high you have a vacuum leak.
The codes
157, you need to test MAF and its wires, read here:
http://www.therangerstation.com/tech_library/CleanMAF.shtml
It reads like a wire issue not a MAF issue
172, is O2 sensor showing Lean exhaust and it is very Lean since O2 isn't changing(switching) when computer adds more fuel, O2 sensors are rated for 100,000 miles, and you can test them by removing them and using a torch to heat them up.
But if you know it is well over 100k miles then change them both, it saves you money in fuel in the long run.
543, fuel pump power is not on when it should be, the PCM is connected to the Fuel Pump relay, this relay is in the engine fuse box, usually labeled FP Relay.
When you turn on the key the fuel pump should run for 2 seconds then shut off.
It won't start again until engine starts, or you turn the key off and back on.
PCM gets the 12volts via a wire spliced into the circuit, so either the fuel pump power is being shut off by relay or the wire to PCM is broken.
If fuel pump power is cycling off when driving then fuel pressure will go down and engine will run Lean, see code 172............Lean O2
So these 2 could be related.
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