For starters, a cheap in expensive thing I would try is put a external 8mm internal diameter star washer (from a local sorce) on the main battery cable at the starter. The star washer sits against the starterm then the cable, lock washer and nut. I saw a lot of this working for a land rover dealer. If that doesn't fix it, check your fuel pressure at the schrader valve above the coil pack ( against the fire wall at the rear of the engine) should be around 55-60 psi. if that is good, check for spark. If you don't have spark, you could have bad coils, spark plugs, plug wires, cam sensor or crank sensor. If you don't have fuel pressure, replace the fuel pump and fuel pump relay (I always do them in pairs). Hope this helps.

Best of luck