I have a late 90's 935 1800 hours and have been experiencing EASY start but will run rougher than crap for the first 3-5 minutes then is smooths out. (similar to low compression problem) BUT if you shut it off and restart it right after it smooths out it goes back to rough running for another 3-5 minutes. <--------a low compression cylinder after warming up wouldnt do that. Go to engage mower and it will nearly kill it. It has LOW power. Oh I also pulled the oil cap while running and it has little to none blow by...So the obvious was to run compression and I was expecting a dead hole with one marginal but what I found was even # across the motor 155, 157, 159. Is it possible that it jumped time or has a valve problem? Anybody have any experience here that could lend a hand?