I have a ford F350 with a 7.3, I am having problems with the engine. When it is running it has a back fire through the intake. It will run but makes a firing sound. It sat all winter and in the spring once I started it, the problem started. Any ideas as to what is wrong?

 

possibly a lifter is stuck and not filling up causing exhaust not to leave on one cyl, blowing it back out intake.