95 ford ranger. Poor fuel mileage. PLEASE HELP!!!!!

Ok its a 95 2.3l automatic ford ranger and it is only getting 17.5 miles to a gallon and i know it can do better than that because its a 4 cyl and also i keep grtting a code for insufficent egr flow could that cause it or is there anything else that could cause the poor fuel milage. I really need help especially seeing how gas is not cheap.