The only solid advice I can give you is - Fuel, Air and Spark. These are the 3 vital components needed for combustion. So take into consideration what components such as fuel injectors may be failing. Maybe the injectors are clogged up and need cleaning. Check that your fuel filter is not clogged and not dirty. Check that your air filter is relatively clean and not completely full of crap and finally check the spark plugs. Take them out of the engine head (with the cables still attached to them) and lay them on the engine head or something grounded and conductive and turn the engine over. If they spark then great, you know it's not the plugs, if they don't, try replacing them and see what happens. Good luck.