I recently replaced my engine in the 93 lude s-type with a F22A, at about 60 mph or so I can feel the engine surging. the only thing that pops into mind right off hand is that the gas in the tank has been sitting for over a year. would this be a possibility or should I check into other components. any help is great!

 

u check your spark plugs and wires? check those and yea your gas could be dirty. your o2 might be about to blow out. on my h22 it would do that at about 60 and it was my o2 sensor. in my opinion just check those and one of those should be your problem.