Hesitates and no power

Engine runs real rough, will not accelerate, water dripping from exhaust. Codes said EGR/knock sensor. Replaced EGR and service engine light went off. Now it took me forty five minutes to go one and a half miles. No power and can hear what sounds like backfires through the exhaust. Adjusted timing with no change. Before it would hesitate and buck like crazy at freeway speed, but, if I stomped on it, it would accelerate but continue to hesitate after I let up on throttle. Also changed fuel filter. Now I cannot get to a shop or afford a code reader. Any ideas?