Arrival Procedure Update Technique Question

[petdocvmd 0]

Would like feed back as to whether I was doing the following correctly.  I'm using CRJ Pro 700 in P3Dv4.5 with ORBX N/S Cali, and FSDT KLAX, KSFO.  My P3D is updated with FSAerodata and apps updated with Navigraph to current AIRAC.

 

Flight was CRJ 700 from KLAX to KSFO.  I filed SUMMR2 .STOKD DCT SERFR.SERFR4 with expectation of Landing Rwy 28L.   ATC gave us DAARK3.STOKD from 25R.  I made the changes in the FMS Dep/App page and executed.  I engaged NAV mode at about 800' and had no problems with navigation on the climbout and cruise.  

 

Just after SERFR, Oakland Center issued FL180 and gave us direct to STINS to expect the RNAV 10L approach.  Seems unlikely IRL because KSFO rarely lands 10s, and I don't think the procedure is even authorized for arrivals at STINS from the SE (due to need for 180 turn).  Despite the lousy ATC, the airplane should have been able to do it:

 

I went to the DIR/INTC FMS page, selected STINS, and hit EXEC.  I believe this should have bypassed all the remaining SERFR4 WPs, directed me (via NAV) to STINS, and flown the horizontal component of the RNAV10L approach.

 

That didn't happen.  As soon as I hit EXEC, the FD immediately led the AP to turn abruptly right, and it was zooming 30 degrees past the track to STINS when I relieved it of it's duties and took over.  I tried HDG mode to turn me back to STINS, but even that started to lose its mind - the AP was chasing the FD needles back and forth, increasingly overshooting like a rookie instrument student near the end of an ILS

 

I turned off George altogether and took manual control.  Since ATC did not see fit to vector me softly to STINS, I overflew it parallel to the NW and turned back around to join the approach, which thereafter went fine using HDG and V/S modes on the AP until 500' AGL, whereupon I finished up again manually and landed uneventfully.

 

Did I do something wrong / incomplete after receiving my ATC direct to STINS instruction?  I re-read the FMS manual, and it looks like what I did should have worked...

 

Any one else seeing periodic wild hunting behavior in NAV or HDG mode?

 

Thanks!
 

Scott