I have a 199 Rinker 330 cruiser with twin 350 mag engines. I am curious to see if you can assist with a problem that I am experiencing. I had the engines tuned up about a year ago and have an issue with one of the engines. The boat sat for awhile and hasn?t had much use. Both engines will run fine for about ten minutes, I suppose until they warm up. Then, the starboard engine will start backfiring, stall out and cannot be restarted. I have ruled out gas, as I switched the line so that both engines run off the port side tank. Any help that you can provide before I call a mechanic to assist would be appreciated.