no
Bad plugs, bad plug wires, carbon build-up in the combustion chamber, incorrect fuel ratio, to name just a few. Consider a tuneup and a fuel system cleaner product at your next fill up.
One cause of your fuel data system not working is a faulty oxygen sensor. Another cause of your fuel data system not working is a defective ignition system.
You may just need a tuneup. Could be a number of things. Dirty fuel injectors, vacuum leak, etc.
Change the fuel filter and adjust the valves.
It is unlikely that the fuel filter would cause the higher fuel consumption. After quite a few years of non-service, a good tuneup would be most beneficial.
It could be lots of things. Start by doing a tuneup. Plugs, wires, filters. If it continues, then perhaps the torque converter isn't disengaging. (automatic tranny) If a tuneup doesn't help, then you'll probably need to get it checked out. It can be anything from a faulty fuel injector, failing fuel pump, poor compression, clogged or damaged sensor(s).
Possibly, yes. If the injection system is not providing a steady and regular supply of fuel to the engine, shuddering and hesitation could result. Note that the fuel pump is part of the fuel system, and can cause similar symptoms if it's failing.
Cycle the ignition on and off several times holding it in the on position for a few seconds each time. Doing this 4-5 times will allow the fuel pump to pressurize the fuel system.
yes they could be stopped up or sucking air into the fuel system
Running rough? Hard starting? reduced fuel economy? Recommended mileage from owner's manual?
It depends on the mileage and if you have followed the manufactures maintanence schedule. If not it would be plugs, wires if you have them, the pcv valve and the fuel and air filters.
Fuel starvation I might guess, check your fuel filter and pump.