hi i recently had an engine put in out of a running car,the engine
starts cold a little roughly, then will miss every 30 seconds or so
and will eventually quit. check engine lite is off ,the  low coolant
light comes on ,but doesnt stay on all the time,, coolant is full.
when you try to pull out it will shutoff , if you nurse the gas it
will sometimes go with little bucking,, if you are at highway speed it
is good and will only complain if you put the gas on .. if it is
idleing and you push gas down sometimes it will quit and other times
it will stammer studder and then rev up . if you jab the gas it pops
and spits but if you still held gas at same place it would smooth out.
it has a new catalitic converter.. and help appreciated,,paul

by the way the time this car had check engine light come on it was a
kinked map sensor line..fixed it and lite was off.