So you're ignoring the advice that a large majority of the time P1128 is set by a failing MAF...?

Most of the time, a vacuum leak will cause an additive code or a P0171 along with a P1128. A vacuum leak is usually more symptomatic under idle or when the throttle is let off. A vacuum leak causing significant issues off-idle would be a large leak, usually causing stalling when coming to a stop.

Check the MAF first.

 

Well I did initially suspect a MAF, the reason that I kind of put that thought aside is because the guy I bought the car from said that he recently replaced the MAF. I'm going to do some tests on the MAF and see what I get.
The only issue I have been having is when I first start the car, normally when its cold, after it idles for a few seconds, the rpms just up and down for about ten seconds, than it goes away. . .

 

Off the top of my head... you could also try a throttle body adapt. Usually, you'll have a code, but it often has to be readapted after the MAF is replaced and the codes are cleared.

 

I am having the same idling issues with my car. I previously had a CEL code of P1176 (O2 correction behind Cat, Bank1), but replaced my MAF sensor and my ECT sensor. Now I have a code of P1128. I have read in other forums that it could be my fuel pump or fuel filter. Did you have any luck fixing your P1128 code?? If you did, details would be greatly appreciated!!

 

The first thing that came to my mind was the TB. Remove, clean, realign.