I just bought a new cartridge of super metroid, it is the US version. maybe im doing the horizontal bomb jumps incorrectly but i lay my first bomb, wait. lay my second. im blown up in the air lay my third. everything is solid. i go the direction i want. but maybe half a second after my third and last bomb goes off. and all explosions are done. no more bombs are out. i hit what seems to be an invisible wall. all my momentum goes to 0. occasionally it doesnt happen. one in every 20 id say. is my cartridge messed up or am i doing something wrong?

It is because after you put out the two final bombs you need to tap right again when you land on the ground otherwise the last bomb won't push you the way you want.

If you're just starting out with SM I'd recommend going for old route with Kraid, Phantoon, Draygon, Ridley order. Less tricks to struggle at and easier to survive. New route is faster by about 2 minutes or so but you could always switch after pushing down your old route time first.

Hi, tutorials can be found here: http://crocomi.re. I agree with the above that if you're new you should most definitely start with Kraid first. However if you are simply trying to learn the diagonal bomb jump then check out tutorials by either sweetnumb, twocat or staticnine. All 3 are great tutorials on the DBJ. I'll try my best to explain the trick in words here:

1. lay first bomb, then tap right (assuming you're going right)
2. as the bomb is flashing just as it explodes lay another bomb
3. lay your third bomb pretty much at the peak of your bomb jump here, then hold left.
4. As you reach the second bomb again you need to tap right to face the opposite direction in morph ball. THIS IS THE MOST IMPORTANT PART!!!
5. After the bomb explodes you towards the right again start holding right on the dpad. Unmorph towards the end for extra leniency in reaching the platform if you are trying at moat specifically.

Hope this helps. Be sure to check out the tutorials I mentioned for better explanations.