Update on slippage in transmission. Don't use synthetic or semi-synthetic motor oil. Thought I was doing a good thing by using UTV/ATV semi-synthetic oil. Owners manual states if you use high quality oil it might cause clutch slippage. Changed motor oil and used Dollar General conventional motor oil 10W-30 and raised idle speed to around 1700 RPM. Most of the issue is gone, will change oil again after I put some hours on the current oil.