1989 Buick Riviera High idle

I've asked about this problem before, but now I have new symptoms. When I did get it to idle okay, I then unplugged the idle air control valve, and the computer now can't make any adjustments to air control. The car idles okay now once it's warmed up, but really low when cold. I think the problem is probably the MAF sensor. I took my multimeter to it and got a reading on the lead of 13.2v, and the signal lead gave an output of 2.4v. What should these readings be?

Thanks,
Harry