1999 Jeep Cherokee Car starts but cuts out

i have a jeep cherokee 99, with a 4.0l and when i start the car up it starts idles for about 5 seconds and then cuts off. i checked the oil and the oil is backing up in the dipstick valve which makes me think there is a blocked vacuum hose or something along those lines. no idea how to fix or if thats the problem. i need help