2.5 TD jumps badly

Hello dear community! Since it has started with us under 0 degrees my omi starts very bad. Must already for some time always 2 times anglow. He is Bj 97 at the start but now I have to pre-glow at least 5 times and then let the starter run very long until he starts.It is as if he only runs on 3 cylinders then runs very briefly 2-3 sec and then it is off. I do this 3 times then run quite normal and jumps again great. Today I also have my fuses n looked through the engine compartment and I always fly out a 30s fuse. Have attached a photo maybe someone knows for what that is and whether this is also the cause.On the photo is exactly the 30s fuse that it always shmells. I look forward to answers