I have a MF35 3 cylinder, when it starts and left to idle it sounds like it misses every few seconds, lots of blue smoke leaving it when idling, it also seems to make a louder sound when it does this. What do you think the problem might be, it starts without heat first time winter and summer.
If the engine isn’t using an excessive amount of oil then I would start by having a look at the fuel injection system.
Start by looking at the injection pump timing, then think about getting the injectors serviced. Check the fuel filters and the air filter.
It is not unknown for the heater plug device to drip fuel into the inlet manifold during periods of non use and cause all sorts of strange symptoms. You could check the manifold after a period of long rest and see if there is any fuel in the manifold.
If you don’t know how to check the injection pump set-up then let us know and I can explain it in detail.
Hope that has given you a few ideas,