Having problems staring my Golf 95 CL - HELP!!

hi guys. I hope anyone can assist. Recently, I had problems starting my golf. When I turn the key, the car turns over but it doesn't start up. I thought it was a cold start problem but I think it's a little bit more than that. So far, I've replaced the oil sensors, spark plug wires and cleaned out my carbirator. I had my spark plugs changed last year along with my timing belt and a new battery. I checked my air filter and it's new.

So far, what I haven't done is change the fuel filter.

What else can I do? Where else can I look.