Need Help Tracking Down a Misfire, 5.0

[MelonMuziq]

Hello,
Ive found a lot of great info on this site over the last couple of years and finally decided to join.
Ive searched this site and others but have not found my specific issue so Im hoping we can figure this out here.

Problem:
The idle would drop down to about 600 and get kinda rough, then it would go up to about 900 and smooth out a little, then drop down again. These cycles would last from a few seconds to close to a minute.
On take off, it would spit and sputter a little with not much power, then when it got above 2000 rpm it would take off with more power. When driving at a constant speed below 2000 rpm it has a bad misfire. Above 2000 it smooths out but still notice the misfire. The check engine light came on so I took it to Autozone to get the codes. It came up with a P0302 (misfire on #2) and a P0171 (bank 1 lean).

Things I Tried:
Replaced ~ Spark Plugs, Wires, and Coil Packs
Checked for vacuum leaks with carb cleaner while engine was running, none found
Cleaned MAF sensor and IAC valve.
After that it ran worse. Now the idle stays constant at 600 rpm and a little rough. Unplugged the MAF sensor and drove it a couple times. Still idled rough and still had the misfire so not much change other than it did have more power.
Tested IAC valve by turning the steering wheel all the way with the engine running and turned on AC but the idle went down not up so I was told the IAC valve needs replaced. Ordered a new one and will put it on this weekend.
That may take care of the idle problem but Im still stumped about the misfire. The only thing I can think of is that there is either a bad injector or a vacuum leak in a very specific area.
Should I do more testing with the MAF?

 

[Turdle]

In my experience, if a misfire is logged on a 5.0 it is a fuel injector issue. that along with the p0171 suggests you should check the fuel injector-or wiring.

You might check compression on 1, 2 and 3 first. Also in my experience if an injector dies and the engine is run too long, a piston will suffer.
If compression checks out , You are lucky. The #2 injector is not extremely difficult to get to. You can get new injectors, and even rebuild kits on ebay. If the injector clicks when you apply voltage to it, it may just have a clogged pre filter screen.

You can rig up just about any led light, and stick the leads into the fuel injector harness. If the leds flash, the injector harness and pcm are most likely OK. If they do not flash, reverse your led test light leads for polarity and try again.
They will flash while cranking, so there is no need to run the engine very long. You might have a helper turn the key for you.

 

[delexploder]

Just for ***** and giggles find the vacuum line that comes from the front of the upper intake , it looks like rubber fuel line and has a clip lock on a squeeze fitting attached to a hard line , run your hand down it as far as you can , BTW it will turn your hand black , I have found this line split on several V8s and it has always caused those symptoms, it may not be your problem but its easy to check other than the ten minutes you're going to spend trying to wash the black crud off your hand

 

[MelonMuziq]

Thank u both,
Turdle, I will give that a try.
Del, is that the one on the drivers side that goes down under the battery? It looks very dry rotted.

 

[delexploder]

Yes it is , its the main vacuum feed for the evap system and I've had it go bad on several V8s and never kick an evap code just cause a ton of problems like yours

 

[MelonMuziq]

Changed out the IAC and the idle is back where it should be. Still not perfect so Im still wondering about the MAF
Changed out the #2 injector and it runs much better.
After getting it back together and triple checking that everything is plugged in, for some reason the heater doesnt blow hot air, just cold. What would be an obvious thing to check?

 

[boominXplorer]

Check the heater control valve vacuum hose, it's on the heater hose lines on the passenger side