I have 1997 2500 conversion van, Just had it state inspected and emission test done. ever thing passed but I was informed that it will not pass emissions next year becouse for some reason my computer will not totally communicate with their equipment, it is not sending out a rpm reading. what could be causing this? has anybody come across a problem like this? my van has the 318 and is in very good condition, but I cant afford alot of money on it. could it be the computer? if I get one you cant return them if thats not the problem,or maybe a loose wire? bad pin? I am not in the greatest condition to play around with it, had a couple nasty back operations. and to take it to the dealer is big $$$. please help.