2003 dipatch van....runs really lumpy?

i had my exhaust break in two, on christmas day!, but i managed to roughly put it together until i could get a new one, which was about three days.

The more i drove it the noisier it got. like a deisel dumper truck!

I had a new exhaust fitted but it still sounds really noise, as if all the big ends are shot.

it starts first time then dies, this happens five or six times, everytime lasting a little longer each time, until i apply throttle a little then its fine but soes seem to be lacking in power.

starts fine for the rst of the day.....dont think it is fuel drain back...would seem fuel/air type thing.

any ideas?

steve