Volvo Repair: Volvo 740GLE problems., fuel pressure regulator, volvo 740gle

Question
The car has 141K miles. It had an AirMass meter, Power stage problems before but they were replaced. The plugs,wires, rotor and cap replaced. It had a glitch for the Fuel Pump Relay also but it is worked fine by removing it and putting it back again. Now, it just cranks over but never starts like what it used to do before. A friend of mine who is a ford mechanic is working on it. Before that no start problem happened it never hesitated in starting. Also, previously it would for no reason refuse to turn the headlights on and with that the radio and the power mirrors won't work. I am sorry for the long question. My friend is saying may be the timing belt is not aligned appropriately or something?
Another problem that I had when it was running, the car used to make only 12mpg in city and around 20mpg on highway. I wonder what can I do for to improve this horrible mileage?

Your help is greatly apprecitated.

Answer
you did not mention a year.I doubt it is the belt.I would first check that there is not fuel leaking out of the vacuum side of the fuel pressure regulator.the other problem with radio and windows is probably a bad ignition switch. there is an electrical part to the ignition on the back side of the key part of the igntion.