Started to lose power when going up hill, changed the fuel filter twice, it will turnover but won't start. When it did run, every time I started up an incline, then it would sputter, lose power then stop. I changed all the plugs, it started right up, idled rough for twenty minutes or so, now it won't start again, it turns over but won't start. I can hear the fuel pump come on when turning the key. Spider? Water in fuel?