Nissan Repair: 91 300ZX-TT clutch slip, motor rough, 300zx tt, fuel system cleaners

Question
Mr Sudderth,
I have a 91 300ZX-TT with 92k miles, the clutch slips like crazy and the gears grind when I shift into 2 and 4.
I was looking for clutch parts online when I found a comment on a parts site that said Nissan suggests that car may have master or slave cylinder issues that cause clutch slippage. Is there any way a clutch could last 92k miles and my slippage is not the clutch? Probably just wishful thinking, but how should I check?
One last question - I took it out of winter storage and the motor is running very rough, like it's only firing on 5 cylinders. Is this common for the Z? Should I bother with any of those fuel system cleaners or go straight to a dealer for a high-price fix?
Thans for you help,
Tim Harrington

Answer
Tim,

If the clutch does not disengage when you put your foot to the floor with the pedal then it would be a slave or master cylinder.  If the car is slipping then it is the clutch.  If the car grinds into 2nd and 4th you will need to replace those gears and syncros.  I would fill it up with super and add 104 octain boost and run the tank to empty and see if it helps.  If not change the plugs and check the injectors and fuel filter.