well to start off i read the forums all the time, but i havent found anything to help me with my problem. my problem is that my batery keeps going dead after about a month, im thinking alternator or MAP sensor. the voltmeter is reading low when starting the truck then moves up to around 14 after about 5 minutes. also when starting. after the initial jump im RPMs when it settles to idle, it will staul out. i have to hold my foot on the throttle at about 2000 RPMs for a while to charge the battery. sounds like alternator to me but i dont want to spend $150 if i dont need to.
thanks.

 

Does sound like an alt, you can get them tested for free at most places so I'd have that done first. How old is your battery? They do go bad after awhile and you can get lemons too that will never hold a charge from day 1. As I said most auto places will test your battery and alt for free, takes like 5 minutes.

The reason for not idleing is probably a voltage issue, but it could also be your IAC, its a valve on the TB that allows air in so it can idle. They get gunked up quite a bit and don't move as freely as they should.

Also not quite sure how you think its the MAP sensor, as that really has nothing to do with the problem.

 

i 2nd the alternator being bad idea.

and yes, if it won't idle or run without sputtering and stalling below like 2000 rpms, your battey is not functioning properly or is not getting a charge.

also another thing to check, is to make sure both of your battery terminals are clean and tight. probably a long shot in your case, but its a free way to help confirm its the batt or alt.
if the battery terminals or dirty, corroded, or not very tight, your battery will not charge properly.
i had a similiar problem and it turned out to be the negateive battery terminal.
here's an easy way to check. let it run for a little while (5-10 minutes) then grab the battery terminals and see if either one is very hot. if one is extremely warm, it means there is a bad connection there.

 

You might want to check your battery for a voltage draw. You can take the red lead from your DVOM and touch it to the negative side of the battery and then ground the black lead. If that reading is very high it would tell you that your battery is being drawn down by something. All that said I would get the battery and alternator tested because this problem sounds like an alternator.

 

Going to 14V after 5 minutes suggests that the alternator is working OK. Also, if the battery has enough power to start the engine, it should have no problem keeping it going.

Getting a battery check is also usually a free service - as was said, a bad one can produce your symptoms.

Checking battery terminals is a good idea, but if that doesn't show the problem, look for loose ground straps. Most vehicles have several ground points - to starter, to engine, to body. I've seen some very weird behavior and sneaky behavior that was finally traced to a bad ground.

 

i 2nd the battery terminals.. my power wire was loose on my old truck and i couldnt figure out why every morning the battery was dead