i just bought a ford f350 7.3 is my first diesel truck so i have a couple of questions to see if anybody could help:

Service engine soon light comes on when I hit the gas hard after a minute disappears.
In the morning transmission will take long to get the 1st gear after i put it on drive after that works good the whole day.

and when diesel is low about 1/4 the truck starts acting funny, dropping rpm's and leaving black smoke. it happened to me twice so after that i just dont let it go lower than 1/2 a tank and havent had the problem again. i thought maybe my gas meter is reading wrong and when it says 1/4 is running empty.

dont have any idea of what these might be any help?