My tt60a has developed very mild idle surging all the time. Yesterday I think I put in some fuel with water and the engine sputtered badly and wouldn't run at full RPM. I completely drained the fuel tank, replaced the fuel filter, cleaned the fuel pump strainer, and put in new fuel. Now the idle surge is much stronger, swinging a couple hundred RPM with no load. It calms down some under mild load but is still there. I bled the system at the bleed port on the filter and have cracked open the injector lines and let a little fuel spurt out. Still surging. Any ideas?