300/440/550 cutting out

I have an 84 550 with a PJS motor in it. I posted a thread earlyer about a fuel problem and got it fixed.(hole in the main line) Now I am having another problem. I start the ski and ride anywhere from 1 to 6 miles and then the motor just cuts out. Its like someone is holding the stop button down. I try to restart it and it will fire for about 3 seconds and then die again. I let it sit for about 2 min and then try again and it will fire but not run over 1/5 throttle. I have to pump the throttle just to keep it running. As it builds up to about half throttle (running like someone is choking it) it will come alive and then it will respond to any throttle position. It will run like this for 1 to 6 miles and then do it all over again. If I hold it at WOT and then drop down to about 1/3 it will die again. NOTE: When it dies its like the stop button is pushed in. No throttle response at all. I pulled the electrical box last night and everything looks to be hooked up. Nothing melted or shorting out. I did notice the ground wire from the ele box and from the battery neg was corroded (rusted) at the point it contacts the motor. Is it possible that the motor will cut out due to the rust on the ground? Or do I have a stop switch going bad?
Thanks Higs
 
OK so the rusty neg wire was not the problem. I went back to the fuel lines and tore the whole thing apart. When I got to the petcock valve and tore it down it was plugged. I pressurized the fuel tank and out of the (on) fuel line came this 2 1/2 inch long white worm looking glob of crap. It is soft and rubbery. What in the world could this be? I will add a picture soon.
Higs
 
Top Bottom