From this board & the great contributors I discovered that the cause of the rough idle condition on the 88 300ce I just got was a cracked breather hose connecting to the air intake. I bought a new hose from the dealer & spent a few hours trying to attach it. Couldn't get it on. Then, I tried a heatgun to soften the end of the hose. Eureka--I got it on. What a great feeling do have done it myself. Guys, try that heat gun first.
Rich