The engine in my 2003 Dodge Ram 1500 5.7L Hemi is rocking bad and not running smoothly. When I pull the error codes off, I get P0113 and P0172. A friend hooked it up on his machine and got a code for random misfiring and said that one cylinder had no compression. Anyone had this problem, or any ideas on what might help? The vehicle has 80,000 miles on it, and I run only mid-grade gasoline.