engine swap

ive reciently did a motor swap on a 2003 dodge ram 4.7 i bought a good used engine i check it out before removing engine is strong but i installed it and it wont start its got fire its got gas its got everyting fine except it wont start it cranks back fires sometimes but never starts abnybody have any idea i was thinking mabey the computer needed to be programed but my local dealer said it shouldnt needed any suggestion on what is missing ive change the cam sensor crank sensor the coils i think the only sensor that i havent change is the temp sensor and maf sendor but i dont think thats has anything to do with it please any help would be good

I think it sounds like timing. not sure though since you mentioned "coils." I'm sured you checked the spark plug wires for the correct order. Have you checked the fuel pressure? someone here should know what fuel pressure u should be running. Check all the connectors, make sure they have a tight fit. Well that's all I can think of 4 now. Hope someone else give you some more suggestions! Good luck!

ok i talked to local dealer and they said that there is 2 types of 4.7 engine and that there not compatable with each other diferent timing i guess so im just going to rebuild my original one thanks

anytime body! good luck!!