Whats the problem

[Snowman1000]

Im not sure if this is a problem or not I am new to these carburated v8 engines. Somtimes when I start my truck it will seem like its missing for a little while and then it will clear up after a while. Next somtimes after you shut it off the motor ( turn the key off ) it will start to shut off( like its supposed to ) then it will shudder and rev up then shut off like it has a loose ground or somthing were would I begin to look to solve these problems.

 

[Hogback Fabrication]

The problem when you first start it is probably a misadjusted choke.

When you shut the truck off after it is warm, and it keeps running for a couple seconds, that is called "dieseling". It is caused by the idle being set too high, misadjusted timing, or carbon buildup.

 

[Snowman1000]

Does it help narrow it down that it dosent do it very often and also would a slight backfire when letting off the gas at high speeds (60+) help any I am leaning towards timing.