502 mag mpi running problem
 

i have a 502 mag mpi with a 500 efi cam just ran the motor on land after winter. it runs rough spits and sputters and when i try to raise the rpm and clean it up it will get stuck at 2200 rpm and will not come down to idle for 10 15 seconds anyone seen this before i changed the oil and fuel seperator i notice it did this at the end when i was winterizing. still have not done the plugs i used startron in the fuel. thanks for any help bruce

sounds like a intake or throttle body vacuum leak.