could use some help with this headache of an Explorer

[RedDogGurl]

1996 Explorer XLT sport trac.

-Problem 1 - when the heater is on it makes a loud thumping/clicking sound (can also feel it with my feet), for a while i thought it was the blower motor fan since i had just replaced a destroyed one, but earlier today i was checking my tranny fluid and noticed one of the large hoses moving every time my truck made the noise.

-Problem 2 - it has a mysterious humming noise that no one can figure out where it is coming from. at first we thought it was coming from the air filter since it had a hole in the housing, fixed the hole, still making the noise. Now when i am stopped at a light and the humming stops, my battery gauge drops and my lights dim. I'm thinking a vac leak, but i have no idea where.

-Problem 3 - a couple weeks ago i was almost in an accident, and since then while i am moving (forward or reverse, mainly when coasting) i hear what kind of sounds like someone scraping a metal container with a metal brush

-Problem 4 - cannot get the check engine light off. reset the codes and so far the only one that has came back up is P0171 system too lean, i have had this code (and P0174) since i got the truck. i have changed a bunch of things and it cannot get it to shut off

any help with these would be greatly appreciated, have had this truck for over 3 years and it's always something with it. I also have the drive safe & save with state farm and the x-ray diagnostic has the powertrain in red (fix immediately)

 

[Flash]

1. Might be air in the heating system, trying bleeding it out from the hoses.

2.Humming noise could very well be the idle control valve. First try cleaning it out with carby cleaner. Other symptoms sound like the alternator, probably worn brushes.

3. Could be the heat shield from the cat is loose or a baffle inside a muffler.
Maybe something contacting the tailshaft.

4. -

 

[RedDogGurl]

Ok, will have a friend do that, I had to replace the radiator a few months ago, but it's been making the sound longer than that (prob #1 ). Prob 2 I know isn't the alternator, I bought that new not long ago and it's been humming for at least over a year. Prob 3 started after I had my back brakes done and was almost in an accident on a really cold day with icey roads, I hit an ice patch when stopping, my brakes were solid and couldn't stop for at least 30 feet.