Van has a severe idling problem all the way through the rpm range. Replace the air idle intake solenoid. Van ran great for about 45 miles. Then the next morning the symptoms came back. Then it got worse and remained bad.it will run ( doesn't die) just not smooth. The idle jumps up/down about 500 rpm fluctuation, again all through the Rpm range. I fugued perhaps a vacuum leak , but why did the solenoid temporarily help? Any suggestions ?