Also you have adjusted the valves? Some have not been done for years. When dealing properly with the injection pump base pressure it will indicate if you need new filters or the tank filter cleaned as well.

Some fuel delivery pumps have gone softer with age.Very easy to recondition if indicated. You have to watch out for them as well.

A pressure gauge on the system is your best friend. It is worth it in my opinion. You can even gain a little in fuel milage but the 5 cylinder natural aspired engine is not the most fuel efficient to start with.

The turbo five cylinder does better driven the same way for fuel milage. Also the current fuel milage is somewhat of an indicator of condition but you have to pin it down accuratly. By going through this area properly tends to familarise you with the system as well. That in itself is far from a negative.