Should there be a big difference with the MAF plugged in?
 

For a while my blazer has been sluggish and has had really poor fuel economy (10mpg) so today I took out the MAF and cleaned a bit of crud off of it with canned MAF cleaner, didn't physically touch the sensors themselves.

Reinstalled it and drove around for about 10 mins and then the check engine light came on. I then realized that I didn't plug the MAF back in. So I plugged it back in and now the blazer feels the exact same as it was it was before I cleaned it. With the MAF unplugged it drives pretty much the same.

should there be a big difference in how the vehicle drives with the MAF plugged in vs not plugged in? Now the check engine light wont turn off even with the MAF plugged in.

disconnect your battery terminal of your choice and turn on the headlights, let it sit for about 20 minutes. This will fix your check engine lamp.

Definitely the negative... disconnect the negative.

The computer uses the last stored data from the maf if it's disconnected,so the engine will probably run ok, but not right under all conditions.

I've forgotten to plug my MAF in once or twice, on mine it makes the engine stumble a bit off idle, but runs fine.