Have replaced 4 alternaters on it in 4 years, just put the last one one two weeks ago and now the light is on again????????????

Sounds like your Unloader is hanging up. What type truck and year?
1 check air line to govenor make sure no leak.
2 Check dis-charge hose or pipe.
3 Check to make sure air drier pop off valve is not leaking
4 The unloader valve in compressors become gummed up and o-ring break and cause valve to hang up in open position which prevents it from building air.
Good luck

Ok, even if the battery is new, get a voltmeter and measure the battery, if its below 12v, thats the problem. That way you completely eliminate all these factors without a doubt. Also check negative wire from battery to the ground box and connections. It sounds more like a corroded terminal.

Sounds electrical.

Are these factory OEM replacements? I once put three cheap aftermarket Kragen batteries in my Corvette in 6 months, bought a Delco and problem solved, that was years ago. Sounds like your problem is that the car sits to much, if it sits more a few weeks either hook up a float battery charger or disconnect the negative cable to the batt.

misfire can be caused by your fuel injectors also

The ultanator on my chrysler grand voyager was just changed a week ago but the battrey warning light is on again in the darsh board.

replace the charging relay

The alternator drive belt is loose or worn out. If the alternator is driven off a serpentine belt then replace the belt. Inspect the serpentine belt tensioner and replace if necessary. On an 18 year old car it is more than likely defective. If it is driven off a standard drive belt then adjust the alternator to tighten the belt. Inspect the belt for fraying and or cracks and replace if you see any.

Is it the frt wheel sensor setting code again? If so I would check the connectors at wheel bearings I found most often terminal tension weak need to tighten or replace harness

it may work again but that is only temporary it sounds like the fuel filter is clogging up