i had a similar issue awhile back, what i found was causing it was that i had a mouse controler built into my stick and the buttom was worn out and randomly spiking. it was doing random things when ever it felt like it, it was like my game was haunted.
once i shut off the dysfunctional mouse this stopped happening.
now i cant say that this is your issue but it may be something you may wanna take a look at.