Kelly..........you didn't say if you'd changed the plugs. In your shoes I'd change the spark plugs and the wires, also. A fouled spark plug can cause an intermittent miss even thogh it may be firing. I'd also look for blue smoke from the exhaust to see if it was burning any oil, and signs of blowby which would indicate a scored cylinder or rings. If you had a bad lifter more than likely it would be tapping, especially on startup. Hope this helps.