Hello I am having a problem with a 1989 Evinrude E100STLCEM 100 hp motor. When cold the engine is missing on what I think are 2 cylinders. It is very hard to get on plane and low rpm's. After running for about 1 mile I can stop engine and fool around and fish for awhile like 10 minutes and when restart engine no longer misses and runs fine the rest of day. Any hints as to cause would be helpful.