P 1128, 1130, 1115 1119 Help!

[diff operator]

Ok,
As in the title I have a 2000 Boxster 2.7 and I'm getting the following codes:
P 1128, 1130, 1115 1119
The car seems to idle a little low. somewhere about 650-700 maybe, the car has a light vibration at idle, nothing major. When I drive the car is a little rough right on throttle tip in but the car revs fine and drives nicely.
I've searched and seen a variety of causes and solutions proposed.
I tried disconnecting the MAF and drove to see if I noticed a difference, witch I did not. however, I didn't clear the codes first so I'm not sure if I should have or not.
The car had previously sat for a while before I got it, is it possible there is a fuel pressure issue?
By the way, I tried removing the oil cap, there was a slight vacuum, but it was easy to remove, the idle did increase when I removed it.'
Any help would be appreciated