At idle my in-law’s 2001 Ford Windstar with a 3.8L V6 runs fine. When you accelerate it feels like there is a slight miss. As the engine warms up it gets worse. Had the engine light scanned and shows no codes. As it was going down the highway it got worse to the point the driver pulled over. It was then they noticed a funny smell and popped the hood to find it was smoking. Where should I start checking?