It's a 97 long bed extended cab with 33x12.5 I live on longisland it's not very hilly here I never really go over 60 completely stock. I took the silencer ring out and turned up the injector pump up a tiny bit but I'm getting like 100 miles to a quarter tank or not even
Don't trust the fuel gauge for a MPG meter. It just tells you how empty you are, not accurate at all.
When you fill up, top off (fill till the nozzle clicks off) and reset the trip meter. Next time you fill up, fill till it clicks, and divide the trip meter reading by the gallon reading on the pump. That's your MPG.
Reset trip meter, lather rinse repeat
Something that could be hurting your MPG is a stuck open thermostat. Does your temp gauge ever get up to the normal zone? If you replace it, go with a higher temperature one (210 or 215, maybe higher, others could tell you more than I could).
Also, you could very likely benefit from putting on an electric fan instead of the mechanical one. Or just take the old one off (but don't blame me if you have to wait on the side of the road for it to cool off).
Check and adjust your timing. The 12.5 degrees is not optimal for MPG nor power. If you bump it up (again, others have more specifics) you could probably boost your MPG again.
Note that these are all things that will give you roughly 1 to 5 percent MPG improvement (each), and won't make your truck suddenly beat a smart car or civic, but everything helps and things add up.
One more note: If you put in gauges, that would give us insight into how the engine is running and if it is not optimal.