I have a 93 aerostar, about a month ago i went to start it and it made a "pop" sound and blew the vacum hose's off of the back of the motor. it's a 4.0 engine. there are four hose's on the driver's side in the back,one of them go's to the breake booster, i shoved them all back on and it was fine until yesterday....i went down to the store,and when i came out and went to start it, it went "pop" and blew the hose's off again. can anyone tell me what might be causing this to do this ? im at my witt's end. ill be thankful for any help ! ! !

The engine backfired. the fuel mixed lighted off before the intake valve was closed. So the built up in the intake manifold causing the vacuum hoses to blow off. Does that year have a distributor and adjustable timing? If yes- check the timing, and the operation of any vacuum advance/retard units on the distributor.

I know this is an old topic, but if anyone else has the problem...
My transmission modulator started to go down and was blowing fluid through its vacuum tube to the little vac manifold on the engine. The fluid lubed the hose and it and eventually others started popping off. Change the modulator (cheap, but a pain to get to on the passenger side next to the catalytic converter), then replace all the vacuum hoses on the manifold, as they probably are still occasionaly going to pop from the fluid having greased them up.