My avenger needs work but idk what it is!!! help before i go to a tune up!!!?

i have a 1998 dodge avenger es and i am having such a hard time with it. bought it back in march? and have been driving it daily. the problem started back about 2 weeks ago. my car turns on everything starts up. but the rpm's go to 1.5 about and then it drops and shuts off leaving the oil symbol on. i usually have to turn it over about.... 3 times each time and then after going it stalls out and have to do it again. now though it wont idle at all. tried fuel injector cleaner and got the fuel filter replaced. i cant make it idle after feathering it now. i've been told it's in desperate need of a tune up as well as possibly a vaccum leak. please anybody help im stuck and need it running properly again!!! it has 150+ miles on it and my idle only stays at like .6 rpm's again it runs but when i slow down it stalls out and the oil light comes on. please anyone!!! i need to know what i need to fix!!