This could be a problem with the transmission forcing it to go into 'limp mode'.
Anyway you look at it, you're going to need to find a reputable repair shop to run some diagnostics to pinpoint the source of the problem
According to the 1998 Ford Windstar Owner Guide ( 5W-30 ) With engine oil filter change : Both the 3.0 and 3.8 liter V6 engines take : ( 4.5 U.S. quarts of 5W-30 )
According to the 1998 Ford Windstar Owner Guide : ( 5W-30 ) is the preferred oil for the 3.0 and 3.8 liter V6 engines
According to the 1998 Ford Windstar Owner Guide : With engine oil filter change : Both the 3.0 L and the 3.8 L , V6 engines take : ( 4.5 U.S. quarts / 4.3 liters of 5W-30 )
The battery group is 65N for a 2003 Ford Windstar
TAKE THE DOOR PANEL OFF FIRST
You,take,it,to,your,local,FordDealership,And,let,them,overcharge,you,for,parts,&labor...Basiclly..your,"SCREWED"!!!!!
According to the 1998 Ford Windstar Owner Guide : With engine oil filter change : Both the 3.0 and the 3.8 liter V6 engines take : ( 4.3 liters / 4.5 U.S. quarts of 5W-30 engine oil )
take it to a shop.
According to the 2003 Ford Windstar Owner Guide : ( No ) use " regular " unleaded gasoline , 87 octane
Lots of penetrating oil, heat up the studs with a propane torch, and let them soak. This can take up to a couple of days - but it takes a lot of patience.
A 2000 Ford Windstar has a ( 26.0 U.S. gallon tank ) So , if the tank was EMPTY ( 26 x $ 2.56 = $ 66.56 )
According to the 2000 Ford Windstar Owner Guide : The front park / turn lamps take the ( 3157 NAK , amber bulb )