Small Engines (Lawn Mowers, etc.): Honda lawnmower chokes itself when PTO for deck is engaged, honda lawnmower, spark plug wires

Question
We were given a Honda 4514 Hydrostatic riding lawnmower.  I have replaced spark plugs, changed oil and filter, replaced gas, changed gas filter, replaced the rubber gas lines from the gas pump, took apart carb and cleaned thoroughly, replaced starter solenoid, and replaced battery.  The engine starts up fast and runs smoothly.  It also drives around just fine.   The problem is when I engage the PTO for the deck.  That is when the  engine chokes and some gas spit back out of the carb intact.  when I release the PTO the engine recovers.  I took off the deck and made sure all pulleys worked freely.  I also replaced the front tensioner spring.  When I manually work the governor and rev the engine, and then engage the PTO, the deck operation sounds normal. It does not sustain it though.  I'm stuck and do not know what to do...   Thank you in advance...   Ted

Answer
I'm not really familiar with this unit, but it sounds to me like it may only be running on one cylinder. I would get the unit running and try taking the spark plug wires off one at a time(be careful you could get a poke), if the engine dies when one is taken off and doesn't seem to change when you take the other off, this is the problem. If this is it, then you need to find out if the spark is working on the dead one or if it is a mechanial problem.