my intake pressure was -450 - -500. for sum reason it dropped to -180- -200. now my car idles funny. 800 - 1k rpm back and forth. one person said it could be my map sensor said it might have gone bad. but i dont have an extra one to test out. could it be ne thing else? vacuum still shows 15-20 at idle no leaks. and exhaust is smoking white smoke. please help!

 

check all your vaccum lines.