Engine ran great before the installation of the msd box.Sbc.Now the car will not idle.In the directions for installation.It states if this problem occurs.I need to order a diode.Whats a diode and where does it goes?Thanks.  

Good question, can anyone help chris out?  

I've done more research on this.Box is wired up for 5 pin.Going to pull the module and wire up for 4 pin.I believe due to the module is in the distributor.The module is saying fire my way and the msd box is saying fire this way.Causeing the idle problem.Looking at the diode it connects on a wire off the alternator.I dont see how that would cure the idle problem.Thanks mpayne.I'll keep you guys posted.Just havent had time to work on the car.2 bills for the 6a box.Mounted under the hood not in use.I better find time to wire it up!!!!!!!  

Wired up for 4 pin.Removed the module.Car idled fine.Then the car would not turn off with ignition in off position.Thats were the diode come in.Wired the diode to the wire off the alternator.Problems solved.