Small Engines (Lawn Mowers, etc.): John Deer 445 power problem, john deere 445, john deer

Question
I have a 1998 John Deere 445 (22 hp Kawasaki twin engine) that will not throttle up without cutting out and stopping. I have checked both coils and they are working fine. Spark is ok, however, if I take the wire off of either side, it seems to run smother. I had a problem with bad gas and replaced the fuel filter and it ran fine.  I did notice that there was pressure when I took the gas line off of the carburetor before but not now (same thing before the new filter).  It takes a long time to warm up enough to throttle up and then it has power but you can tell that it is rough and will hardly cut going up a hill.  I thought maybe the pump could be clogged somewhat or a break in the line in the gas tank, but it will eventually throttle up.  Could it be a bad valve as they were sticking (from bad gas) and the push rods were coming off.  Re-gaped them and used seafoam and it ran fine, but a few weeks later, loss of power and dies if try to throttle up until warmed up.  Runs ok on flat service but you can tell that its lost power and the engine seems to be rough.  Starts easily without any throttle but will not start cold when throttle half way or fully engaged.  My suspicion is a bad value seat or a fuel pressure problem.

Answer
I see you've done a lot of work checking spark, valve adjustment, fuel flow and many other things. My question is, have you taken the carburetor off and cleaned the jets out. If you had bad gas in it enough to stick the valves, I'd bet the carburetor needs a thorough cleaning. Make sure you clean ALL the small passages, not just what you can see.