Well, when I go out to start my truck, I can't get it to crank. I go to my plugs and take one out and try to get it to fire and it will crank up. I turn it off and put the plug back in and it will run fine for a few days then it will do it again. I go to the same plug i used before and it won't work sometimes I have to go to several plugs to find one that will fire. It is getting worse now and doing a couple of times a day. What could this be? I have been told that it could be a chip going bad. In my research online I have seen that it might be a crank sensor. Any help would be appreciated!!!!!!