Mitsubishi Repair: 95 Mitsu Galant S, stepper motor, distributor cap

Question
Yesterday, I drove my car to work with no problems (other than will be mentioned below).  When I got back into the car to go to the bank, I put the car into reverse and it stalled.  I have not been able to get it started since.  In checking for spark, I found that there was little or no spark on the number 4 cylinder and none at all at the 2 cylinder.  I didn't check the others.  I made sure the distributor cap and rotor were fine, and also double checked to see if the car had "jumped time", which it hadn't.  

Previous to this, I was having a problem with the car idle as it would be so low you would need to brake and hold down the accelerator at the same time.  However, after putting some fuel injector cleaner in the tank after a fill up the past couple of times, this problem seemed to be clearing up.  Before that, periodically the car when idling or slowing down, the engine would race, then drop off on a constant basis.  Usually restarting the car would solve this problem.  Would these problems be related and what would cause the no spark situation?

Answer
Brad,
A variable idle can be caused by a faulty idle air control (IAC) motor.  This little stepper motor receives a signal from the car's computer to allow a specific measure of air into to the intake to keep the idle speed at a constant.  Though a faulty IAC may not the be overall cause for weak spark plug firing.  If a spark plug is not receiving spark at all, you should check your ignition coil, distributor cap, rotor, spark plug cables and spark plugs themselves.  You mentioned you already inspected your cap and rotor.  But if it's been more than 30,000 miles since you replaced your plugs, wires, cap and rotor, I'd recommend you do so.  You should check to be sure the ignition coil is putting out enough power.  It's possible the coil is worn and is not providing enough power to be able to fire all your plugs properly.

It is best to replace all regular maintenance items first before you start spending lots of money on mechanics repairs.  It's possible a simple tune-up will remedy your problem.  Looks can be deceiving when inspecting parts, so replacing items that should be replaced anyway is a good way to at least rule out the most common causes.
Good luck!