'99 ford windstar dies while driving

so before i took my car to a Midas to change my oil and rotate my tires and did what one of there services to check hoses and belt and my check engine light ect... i knew my car was having a transmission problem and it needed a fuel injection service i drove the car like that because i cant afford to pay for replacement for a transmission for 99 ford Wind-star i had already change that transmission 2 times and there it goes it slips and has sort of hard shifts! but that's not the question the question was that in the morning when i took my sister to work before i took the car to Midas it wouldn't turn off at all but the R.P.M would just go down a little so this time in the morning after 2 days i took it has turn of on me at least 5 to six times at every stop i do and the car would shake drastically i don't know what it is can u guys help me out with a guess at least!!!

Response:
1) Start the engine and walk to the tail pipe. Can feel the exhaust under pressure, does it sound like a whistle? Now look under at the pipes and see if any are crushed or something in the tail pipe.