When I am driving and apply the brake my RPMs drop and so does my oil pressure, then my oil pressure light comes on and my truck dies. I do not lose any lights or anything and my truck does not "puttter" out it just dies. I changed my fuel filter (as this was recommended to me) and also I unplugged my oil presure sensor (?) Next to my filter(as I was also told to do that) and started my truck and it still runs. As of now I am stumped. Where should I go next?