Hello, so about 3 months ago during the winter time I noticed my chevy will have a hard time during cold start. Sometimes it will start but rpms will drop then go back up again and sometimes it will fail to start at first time. After the car warms up even I turn it of it will start from the first time with no issues at all. I drove the car to a mechanic who replaced the alternator, battery, spark plugs, oil filter and fuel filter but he wasn't really sure what was causing the issue. Anyway that did not resolve the issue and the problem continued. After that I took the car to the authorised Chevy dealer. The car was there for 4 days and all they told me afterwards was that there was low compression in all cylinders, however the numbers they told me seem too low ( for 1,3,4 cylinders - 4atm/60psi, and for 2nd - 2atm/30psi). They wanted to do basically a full engine repair which costs a lot of money and I am not sure if it's even worth going for. I read about on this forum that there is a fuel sensor that could potentially not be delivering enough fuel to the engine at cold start, however at the shop they told me that there is no such sensor. I am really confused at this point and have no idea what to do. If someone has any idea what the problem could be or has tackled with something similar I would really appreciate any ideas. Thank you.

Oh also I want to add up that there is no check engine light which is the reason I am so hesitant to this repair. How can the car according the mechanics, be on the verge of not starting at all without the check engine lighting up?