I have a 2003 Impala 3800. When decelerating the engine will surge from 1100 to 1400 rpm. For instance traveling at 65 you take your foot off the gas and start to slow down to approx 55 rpm drops to about 1100 bounces up and down a few time to 1400 then settles down to 1100 until your almost stopped. Does the same thing in any gear (different speed of course). The car does have a bad MAF sensor. Could this cause that or is there something else I should look at.