How to limit the bandwidth of an opamp?
As far as I understand the question, your problem is with your phase and gain margins of the Op-Amp. 
To solve this problem, you might have two options, first you can add a compensation capacitor at the output of the Op-Amp (between Node14 and ground). The cap would reduce Unity-Gain Bandwidth of your Op-Amp and hence corrects your phase margin. 
Second, you can reduce gain of feedback loop (the feedback here is the wire from emitter of Q1 to node 13). In order to reduce feedback loop you can simply use a resistive divider.
These topics are addressed here:
http://www.mit.edu/afs.new/athena/course/2/2.010/www_f00/psets/hw3_dir/tutor3_dir/tut3_g.html