Good morning,
I have a heavy duty clutch and not sure when it was installed. But my car is getting stuck in the gears every now and then could that be a clutch going bad....???

 

No sounds more like the clutch cable needs to have some slack taken out of it. The clutch is not fully disengaging.

 

I don't have a firewall adjuster. how else could I adjust it??

 

You have to push the pedal down and then hold the quadrent from moving with a screw driver or something then slowly lift the pedal up and you will hear it click. 1 click at a time until you can easily bring the car into and out of gear easily. If you take out to much slack it can cause the clutch to slip so 1 click at a time until you get it where it needs to be. Usually 1 or 2 clicks is all you need.