Yeah, sounds like the valve seals. I have had a couple of cars in the past that did this. It was very embarrasing to say the least. I would dread seeing a traffic lamp turn red, because I knew the results when I would accelerate.

I was once considering a 1993 Lincoln Town Car, with 77K actual miles. It had the 4.6L engine, which are very reliable engines, but these were well known for this design flaw. It was like new and well maintained, but it already had the problem.