1996 Ford Windstar chugging at idle speed mostly

New wires, plugs, fuel pump, injectors, fuel filter, air filter, upper intake gaskets, cleaned mass air flow sensor, cleaned intake, oil in intake tube and intake and van chugs slightly, tried spraying intake cleaner around all could think of to check for crack upper intake or vacuum leaks, none, When apply small vacuum to egr seems to make a difference on engine rpm so I think it is working properly, not positive about fuel regulator or how I can test. I don't think that catalytics are blocked because I seem to have good power. Seems like chug mostly at idle speed and most noticeable when in drive. Hear popping sound - sputter like. Pressure out back of exhaust is puffing, popping. Any tips, also cleaned and replaced one o2 sensor that looked like could have been damaged. Any tips?