Which GPU is installed for pictures 1, 2, and 3 in your last post?
The engine model, assuming the engine isn't damaged (you can try performing maintenance via the SR22 Maintenance tab), as it only approaches near clouds, this signifies significant performance anomalies with the machine. Based on the screenshot sent, it does seem that the machine is GPU limited. Based on both GPU options, even the 1070 should be sufficient.
If you can, send over a log.txt file from the sim from when it is doing the stuttering and that should help give a better picture on what is going on.