92 cherokee accusound by jensen

So I have a customer in today who had his FR speaker cutting out, but it mysteriously turned back on for me before I even touched it.  Ohms were fine and I wiggled the boot to make sure the wires were not open.  No affect.

Pretty much narrowed down to the Head unit or possible amp?  Does this year have the an amp in the vehicle between the head unit and the speakers?  Or were they on the factory Jensen Accusound speakers?  I never got to see the factory ones.   I know the 93's have it under the rear seat, but it is not there.  Also what ohms were the factory speakers?  We put 4 ohms in.

If there is no response in about 5 days and if he is still having issues I will just recommend a new deck.