Hey! I am new to this forum, and new-ish to this car.

Recently we replaced some stuff to lessen an oil leak (valve cover gastket, oil filler cover gasket, and the flame trap in addition to a vacuum hose leading from the flame trap). Now, the car decides that it doesn't want to go more than 20 miles an hour sometimes (especially those times where you need to go faster). I would immediately say transmission, however, it isn't revving high and unable to change gears, it just doesn't appear to want to go any faster.

Could this be due to anything that was fixed this past weekend? Any advice on what I should check? Some folks have recommended the kick-down cable (if that's the case, what I am looking for when I look at it?).I am resourceful, however, by no means am I mechanically inclined (thus, why I have my father help me actually fix things).

Thanks!