Rough idle

I have a 1999 ford f150 lariat, it just started to run rough out of the blue, like it had a bad mis in it, check engine light came on. When I have car in park you can barely feel it but when I put it in reverse or gear you can really feel it misfiring. Rough idle at slow sppen but kind of gets better when the rpms get higher. Could this be bad plugs or water in my gas? I used gumout jet cleaners beacuse it felt like maybe the injectors were getting dirty. Please help lol