Crank but no start

I asked this question a fews days ago and really didnt get an answer. I started my truck the other day and drove it one mile and shut it off. Now it cranks but wont start. I can hear the fuel pump run so I know its not that. When I try to crank it now the positive battery terminal gets really hot. The connection is good. I dont know if that means there is a short somewhere or what. What could possibly be the problem why it wont start. I dont know where to turn. I really need some help. What should I try and what should I look for. HELP PLEASE!

After cleaning the battery connector wires with baking soda and white vinegar, cleaned and re tightened a few ground wires in the engine compartment and not only started up but is now running smoother and no longer throwing codes. Thank You for great suggestions. Dave

Still not running right. Still having problems. Went to o'reillys and had the codes checked.P0440 with the emissions.I know that the spark plugs need to be replaced and ordered motorcraft sp432 plugs. Have new wires and the coils are OK. I am also trying to check the IAC but need to know the procedure to do so. The cat has been removed prior to me purchasing the vehicle. Just still not running right. Is there a way of checking IAC with an ohm meter or a different way. Driving me crazy. This is how it is. Need suggestions. Or do I need to check something else. If you fnd the time get back to me. Dave

I shut the truck off and went to restart it. It cranked but would not start. I hear the fuel pump running. When I try to crank it the possitive battery terminal gets really hot and sparks. What is my problem?

The connection is good that shouldn't be the reason it cranks but won't start. Why it's gets so hot must mean a short maybe in the starter. Why is it getting hit and why won't it start even though it cranks?