recently i had blown the engine in my rs and had another one put in..but it is opposet of alot of engines that i have seen in the same car that i have...the garage that put it in said it was from a 99 gs..it had the vaccum lines for cruse control that i had to plug but i changed out the spark plugs and it still idles a little rough..no oil on spark plugs and all cylenders are good..aI did a leak down test and im at 35 to 40 on each..could anybody give me a clue on the 420 and how it is suppose to fit in 97 rs please