Nissan Repair: 2001nissan Frontier, mass airflow sensor, air sensor

Question
hello,
i recently bought this 01 frontier 4cyl with 120,000 miles on it as a point A to point B truck. since i bought it i have had to change the alternator, 02 sensor in bank1,and battery due to the alternator draining it. now i have a major problem, i can start the car just fine and run it during the day ok. but whenever i come to a stop after driving at 3000 rpm's or more it wont hold an idle, the needle drops hard and kinda bounces as the truck tries to stay alive but without me stomping on the gas it never will. HERES THE CATCH, the situation i described above worsens when i have anything else electrical (wipers,headlights,radio, and the A/C is the worst)running the truck wont hold an idle after i have had to drive past 2500 rpm's. The mechanic at the dealership here in town told me that it is for sure a air sensor (cant remember name) of somekind that monitors fuel to air mix?

problem number two is when i put my truck on jacks to change the alternator i noticed that the front left tire makes a clicking noise and had some play to it when i grabbed it at top and bottom and wiggled. i then took the tire off and did this to the disk, no movement? is it the tire?
if you could tell me anything about these two issues and the probable cost of repair or if i can do it myself i would really appreciate it.

thanks alot

Answer
Josh,

The idle problem sounds like you have a battery going down.  I say this since you say it is worse when things are running that load the electrical system.  If you do not have any check engine codes it could well be the mass airflow sensor also.  But, seems to be electrical and not engine control related.  The click and movement will be greater with the tire on since you have more leverage.  Tire and wheel off you do not have the moment arm, distance, from center.  You could do all yourself.  Autozone or Checker will do a load test on the electrical system for free.