Hi everyone I am new to the forum and I really could use some help. I bought a 08 Scag Turf Tiger (STT61v29DFISS) with a 29 Kawasaki DFI Liquid Cooled (FD791D-CS04) and a 61 Velocity Deck with collection system 740 hours. I have owned a Wildcat 61 with a 27 Kohler and a 48 Tiger Cub with a 19 Kawasaki. I had no problems mowing with the the other two but this Turf Tiger is causing me problems. The mower starts and idles fine and the rps sound good too. The problem is I lose power when I engage the PTO for deck. The mower does well on hills and will climb them with little or no issue without the deck on. When I turn the deck on the mower will drop RPM's significantly and almost stall. I then have to back off the wheel motors and let the rpm's catch up. I took the bagging system off and I had the same issue. I just pick this mower up two weeks ago and the previous owner said that there were no issues with the unit. When I got the mower I changed all the filters, oil and hydraulics. At first I thought I had air in the hydraulic system but I don't believe that is the case since the mower clibs hills well without the mower deck on. I tried calling my local dealer who can't pffer too much help because he is not too familier with the DFI. I called Scag and they said it could be a coil but they are not sure. If anyone can help me diagnose the problem that would be great because I really need to get this thing mowing again. Thank you all in advance for any help you can offer.