there are many strategies for this situation.
My way - I've never noticed the inability of the AMGs to hit a stationary target, but you can lock up a capship outside of their flak range (like stated earlier around 12k-11k). As soon as the flak starts up increase to attack speed and wait for the AMG's, jinx slightly, to avoid the AMG, but not enough to loose your target lock. If you can't jinx and keep the target lock or take an AMG hit, abort the run. When you finally get a lock, afterburn to about 4000 out and then dump the torp between 3000 and 2500 out, being carful not to turn right into the torpedo you just launched (done that quite a few times) - in otherwords don't climb very sharply.
The problem you seem to have is getting to this point with enough of your ship intact. This is tough considering breathing on the Sabre can knock out an all important torp or the even more important targetting system. You just have to find a strategy that works for you, but an unconventional one that works for me sometimes is to scuffle with the wing of fighters attacking you, allowing you and your wingmen to weaken their shields. Then afterburn towards the 2 capships and fly between them, all or most of the fighters will follow you and be weakened by the first onslaught, the flak spread the capships put up, the occasional AMG kill, the occasional crash into the capships, and your wingmen plinking at them from long range. After your out of flak range, turn around and engage again, hopefully with weaker or less fighters than you faced before.