last time out my 115 has been shuttering at certain rpms 2100 for instance I can feel it in my feet and in the wheel ,also its been not starting like it use to ,it always cranked on the first rev and still will when cold but after its ran for 1/2 hour or so it takes 5-6 more turns before it starts and ideas runs on XD 100 since new and its got maybe 28 hrs by the I command tach