#1 I would replace the oprod spring with a known good spring. The symptoms of a weak spring are sometimes confused with being under-gassed, because you get such high bolt velocity that it skips the second round or will misfeed. You didn't quite fully explain the details of the malfunction so I don't know if this is more or less applicable. Is the bolt picking up the second round and failing to feed it because it doesn't have enough "oomph"? Or is the bolt picking up the second round and it's jamming? Or is the bolt skipping over the second round completely and returning to battery on an empty chamber? All 3 scenarios could be considered "the bolt not taking up the second round"
http://www.garandgear.com/m1-garand-spring.html
https://www.brownells.com/rifle-parts/receiver-parts/recoil-parts/recoil-springs/m1-garand-operating-rod-spring-prod38877.aspx
While you have it apart, clean the gas port out with a #47 drill bit. If the port is fouled, gently spin the bit with your fingers as you clean the port. DO NOT USE A POWER TOOL OR A BIT HOLDER. If you're malfunction is from being under-gassed, this is the easy and most likely culprit.
Most military surplus .30-06, like the HXP greek, the PS/KA Korean, and the LC is as "garand friendly" as factory ammo gets, from a functioning standpoint. So, I'd rule ammo out of the equation unless you didn't have one of the above "flavors" of surplus.
I would say with 90% certainty, if you did both these tweaks, your gun will run. The nice thing is, you should do those two things anyways, so it's a perfect starting point.