the engine gradually lost power,checked plugs they all were fouled,replaced them

It could be the fuel pump and filter. I was experiencing problems similar to yours. Sluggish acceleration, even when I was pressing the gas pedal all the way to the floor. It would sometime cut off on me and after it set anywhere from 10 to 30 minutes it would start and sometime cut off. It would also make noise, like the fuel pump was struggling. So I had the fuel pump/filter/strainer replaced today and right now it is running great. You might want to check around for estimates. I got one from Aamco for $738.00, then I, well actually I got a quote from BrakeMaster a month earlier for $425 and they said they would match my cheapest estimate if I found one cheaper. Should have stuck with them in the first place because I like them from previous work on my car. So they replaced it, the noise stop and my car runs great. My sister told me a year ago at time while she was following me on the freeway that my car was also emitting white exhaust from the tp at times. I had my intake manifold gaskets replaced earlier because it was leaking but it still cut off after that. I would check both out, good luck!