92 Sierra performance Question

I have a 92 Sierra,305 automatic,which I drive 26 miles a day to and from work.I only average 16 miles to the gallon and am looking for advise on how to improve,like K@N air filters, will these help?So far everything on the truck is stock including,Accel plug wires,new distributorcap and rotor,sparkplugs,ignition module.Would a MSD ignition improve fuel economy?Thanks in advance!

Systhetic oil in the engine, differntial and transmission.

Nothing is going to improve the mpg enough to make the work worth the costs of the upgrade. You are pushing over 2 tons of truck down the road and that takes fuel. You will spend hundreds to save only pennies. K&N filter is never going to give you any mileage nor is an MSD ignition, its just going to cost you money that you could be spending on fuel.

I had a 1992 Chevy Silverado with the same engine. 16 mpg is average for a 4x4 truck, my 2008 GMC is only getting 18mpg and these engines are more efficient than a 1992. You either got to bite the bullet and live with the mpg or get another vehicle to drive to work and save the truck for when you need a truck.

PS-Before you dismiss my advice consider I have owned 4x4 trucks dating back to 1975 so I know a little about the mileage and tried many things to no avail.