posting for a friend--claim is when he start's the motor run's like a top. But after 30 or so minute's start's to run like crap. New gas,gas line, new plugs ??? Any idea's

Ignition? That is something that can cause problems after warming up. Had the problem on my truck, and looks like my brother is having the same issue with his 16hp lt. Same on his, we've cleaned the carb, new plugs, filter's, etc. After running for about fifteen to twenty minutes it bogs down. Will probably be changing out the ign soon.

My 27 PD is brand new and was pulling the same thing. It turned out to be totally gas system related. It'd take a long time to start farting and running crappy but it would and then it'd just stall, I ended up going to a bigger gas line, shortened it up to the minimum length I needed, replaced the priming ball and put sealer on all the hose barb connections when I redid them. This completely elimiated the problem for me. It's amazing how little a leak you need to lose good flow.

It would also stall when I came down off the revs so I adusted my idle up to about 1350 and that fixed that problem.