Murray 11hp rider... engine surges. Dies out after a few minutes. Put fresh gas/plugs/fuel and air filters/. If I manually play with the linkage for the butterfly, I can keep it running. If I let it alone it dies. Any suggestions? Thanks, Steve

Let me guess... you leave gas in it all winter?

Sounds to me like varnish buildup on the jets causing a lean mixture.

What I do once a year is get a can of Seafoam and dump it into 5 gallon can of gas I use for the lawn equipment. Yeah that's a heavy does... but it did cure a surging at idle 20 hp Craftsman tractor. And made some old mowers easier to start.