As for outs in Omaha H/L, we have to be careful about whether we are asking about outs to improve our hand or about outs to the nuts. It sounds like you are asking about lo OR hi outs. The three "x" cards are still important, as there may be some backdoor opportunities still as well as plenty of 2-pair and 3-of-a-kind runouts left. Since we are at the flop, there are two cards to come.
This 3h4h has very few nutted
hands to hit. a 4 high flush is a long way from the nuts, and your 5 or 6 or even 7 high flush won't be the nuts either. The closest thing you have to any nut type hand is the nut low, which you may end up chopping anyways. So most of the outs here are non-nut outs. This is a very important distinction when considering outs.
Outs to improve our hand:
4 aces give a non-nut 5 hi straight, and a
nut low (but possibly a chop)
4 sixes give a non-nut 6 hi straight, and a possible low.
7 remaining hearts give a non-nut flush (easily beat)
3 remaining 7's and 3 remaining 8's provide a possible low
3 remaining 3's and 3 remaining 4's provide a pair (your right, not worth much)
2 remaining non heart x1 and 2 remaining non heart x2 provide a pair (not worth much)
31 outs to improve your hand, but only 4 to a nut low and none to a nut high.
Backdoors:
a 6 AND 7 provides a non-nut 7 hi straight (only count 3 non heart 6/7's here for about a 1% chance - equivalent to 1/2 an out)
a 3 AND another 3 for a non-nut set (a pair on the board provides possible boats for opponents - ~.3%)
a 4 AND another 4 for a non-nut set (~.3%)
a x1 AND another x1 for a non-nut set with non heart outs (~.1%)
a x2 AND another x2 for a non-nut set with non heart outs (~.1%)
A myriad of possible 2 pair runouts (~4.0% for equivalent to about 2 outs)
Don't know what other possibilities there are with the 3 x's.
All in all, there is approximately a 6% chance of backdooring some of these hands, equivalent to about 3 outs.
Interesting question. If I were facing a bet here, I would not feel very good about much of this hand. No nut hands and even our strong hands are vulnerable.
Good luck and God Bless.