I just recently took my ZG20 to get some maintenance...all fluids changed, new spark plugs and filters. Mowed one time and it started acting up. The ZG20 loses power when engaging pto at full throttle but regains power when PTO is shut down. The ZG20 also loses power when going full throttle trying to accelerate but regains power when I slow the mower speed down. Started simple to find problem. Replaced new plugs with new plugs...same problem. Siphoned old gas out and put in 93 octane...same problem. There is no noticeable fuel leaks nor can I smell a leak. Checked fuel filter...looked good and arrow was pointing in correct direction. Air filter and the foam around the filter looks good as well. My mind is thinking coils but I ran the mower at mid throttle with break locked and the engine never missed. Did the same for full throttle only missed maybe 1 time in 60-90 seconds intervals. I never had a problem with the mower until I took it in for maintenance. Any help is greatly appreciated. Hopefully its not the dreaded coil replacement but I honestly believe its fuel.