That yellow box is the speed control module! IIRC from my 18 years as a Jeep dealership mechanic, it was originally either duct taped or screwed to the top of the under dash A/C unit!
For a lack of power and poor economy, try checking the vacuum advance in the distributor. Replace it if it’s inop. Also, they are often de-tuned! On the original Motorcraft electronic distributors, the vacuum advance is adjustable. An 1/8" allen wrench into the vacuum port will allow adjustment on how quickly and how far it will vacuum advance. Try turning it 1 turn at a time to see how it reacts. If it now pings, back it off. IIRC, counter-clockwise will allow a faster advance and more of it, to a max of +10 degrees.
Also, for poor economy, test the power valve in the carb. Some have a vacuum line running off the housing back to the rear cylinders. If the valve is bad, it will leak gas through the vacuum line into two of the rear cylinders. The engine will run rough and you will find raw fuel in the line. Some have internal passages for the vacuum to the power valve, all cylinders will run rich with these if the valve is bad. The carb is really easy to overhaul, the kits come with new valves.
Hope this helps!