Go get a hand gun. Shoot yourself in the foot.
That will have roughly the same chance of fixing your check engine light as guessing.
The code format for early OBDII stuff is PXXXX, all Xs are numerals, 0000 is not used, 1000 is system check incomplete, this leaves 9997 possible codes (not all of them are used or would apply to your truck), figure an average 10 potential causes for each of them, we will call it 3000 codes used in 95, so 30,000 potential issues.
Like I said, shooting yourself in the foot will be about as effective as guessing. It might be more effective because you will have a gunshot wound on your foot and won't give a flying f*ck about the check engine light.
EDIT: This post is meant to demonstrate the futility of guessing as a diagnostic processes. It is not meant to suggest that anyone should actually go shoot themselves in the foot.