1998 Chevy S-10 Failing Fuel Filter/Fuel Pump Questions/Sym

1998 Chevy S-10 Zr2 Pickup. 140,000 miles. Sensor for gas tank has quit working months ago, been keeping track by odometer. Ran out of gas 4 times in past 6 months, since then, small issues have arisen. Less power when accelerating, tends to slightly bog down or rev up while driving, even with steady foot control on accelerator. Gas mileage has decreased, I'm filling up more than usual regardless of gas prices. Are these failing fuel filter/fuel pump symptoms; in need of timing and spark plugs (overall tune-up)? What do you think the problem is?