318 MAX fuel economy builds?
I’ll have to say my 1987 E350 Ford van with the 460 bought new and has 49,890 miles. Replaced the intake gaskets back 17 years ago, ..., removed the pumps and egr tubes at the same time. Rebuilt carb 3 months ago (sat for two years without starting) runs great and never saw any coke...
First, you disabled the EGR, so it couldn't contribute to any coking. Second, this may add credence to possible excessive blow-by causing heavy oils in the PCV on Rat Bastid's Ford.
For the OP, what is your budget? If it were me, I'd start with a good tune-up and get a base line first. If I improve things, I want to quantify how much. My definition of a GOOD tune-up is good air & fuel filters, new PCV valve (and probably replace the PCV hose to the carb, and clean the PCV port in the carb), and brass terminal cap & matching rotor (Blue Streak or NAPA Belden are 2 examples). Next, I'd use solid core wires. Granatelli makes solid core 8 mm wires with an EMF suppressor ring that will work even on the latest computer controlled engines (like the LS & G3 Hemi which still uses ignition wires). Third, I personally would use non-resistor spark plugs from Brisk. Yes, NGK, Autolite, Champion and so forth make "non-resistor" spark plugs, but they still use a 1k ohm resistance (instead of the normal 10k ohms in normal resistor plugs). Brisk's Silver line has less than 6 ohms of resistance (their normal non-resistor plugs measured in at 220 ohms). Believe it or not, I'd clean the EGR passages and verify the diaphragm holds vacuum; test the thermo-valves (in the radiator?) to make sure they worked. EGR can actually help in some operating ranges. Then I'd drive it for awhile to get some numbers.
While in this phase, I'd try tweaking the ignition timing 2 degrees one way or the other to see if it gets better. If worse, go 4 degrees in the other direction (2 degrees the other way from baseline) and test again. If better, try 2 more degrees. This is also the phase to iron out carb, tranny, electrical, and other issues. Assuming nothing tragic rears its ugly head, I'd work on the next phase in about a month or 3.