The lift will gate open about 6 inches and stop. I then have to manually finish opening lift gate. Must manually close also. Here is the weird part - it is intermittent. Sometimes it works fine. Same thing whether I use keyfob, handle on liftgate on button on overhead panel. Seems like it is electrical or a stick switch. Any suggestions how to troubleshoot. This starting happening after sun roof failed and they wanted 9k to fix.