Bought truck. Owner said it need the spark plug and wires changed. Did that, wouldn't start. As of now have replaced spark plugs and wires, fuel pump, left catalytic convertor, air filter, and the fuel filter. Wouldn't start. Removed air intake on the throttle body, with throttle flapper propped opened p/u started and went up to 2000 rpm and shut itself off. Looked at catalytic convertor and it was red hot. Black smoke came out tailpipe. What's next?