Vehicle starts right up but when you put it into gear it starts back firing and

any work done on the engine recently?do you know what size engine is in the van,cause their are 5 different ones it could be?if not what is the 8th digit of the vin#.WAIT a minute! did all this start before or after the game Thanksgiving Day?you member,THEM Panthers and them GIRLS?sorry,i guess i gave away where i live.