Curtis Marconnet

My 2020 General 1000 is hard to start when it is cold. The altitude where we live is 9200 feet. During this last winter after 8-10 tries it would start and idle for about 45 seconds and die. I was able to restart it it would run fine. I run 85 octane in it. I just got it back from a dealer that checked the fuel pump, the injectors and fuel filter, they said everything are good. Can anyone help me with this problem? Thanks