1998 Lincoln Town Car surge

Hi I have a 98 lincoln towncar and when the engine warms up it has a surge around 30-40 mph I replace spark plugs all coils and boots fuel and air filter cleaned the whole throtle body even took it to a repair shop, no lights are on and also cleaned the maf sensor but did not replace, I think it's a trans problem I read that these trans on the 4.6 motors have a oss sensor that goes bad can some one please help so I won't pull the little bit of hair I have out?


o forgot to mention runs like a top at idle