Service engine light stays on

I have had my 1998 windstar for 2 months now. My service engine light has been on every since I bought it. I have taken it to a few places and each time I have gotten a different story. One time they said it was my fuel filter I changed it and that didn't help. The next time they said it was my O2 sensor. I took it to another mechanic they put it on a machine and came up with codes 153-154-171 and two others I can't remember. I am getting really fustrated. Can anyone tell me what the problems are and how to fix them? I have been having problems with my dome light and door ajar light. I would like to know how to fix them too.

which engine? if its the 3.8 with the crazy plastic intake, they have a problem with the o-rings on the upper plenum leaking because they get hard. this would set a lean code, 171. the 153 MIGHT be due to the lean condition. the 154 does not show up on the code list so i dont know what to tell ya there. also the 3.8s have problems with head gaskets. the coolant leaking into the cylinders may not be doing anything noticeable now but they can take out an O2 sensor pretty quick. your mechanic should be able to see coolant on the o2 so that may not be the case.