I have noticed this very often, when I shoot a cloaked enemy, they don't come out of it and it appears that their energy isn't trained, I put a few bullets in them, see the blood flying but nothing, I have to shoot them again to make them uncloak but when I get hit even with one bullet while cloaked my energy is drained immediately to zero. Could this be because of lag and have anyone else noticed this?

There is a small delay, but thats all

i think it is because of lag
there is some probability that you got a cheater

No...

How Stealth works is...Your suit energy is all being channeled to stealth. If you get shot, the damage goes directly to your Health, not to your suit energy. So even as you continue to die, the Suit still dedicates that energy to Stealth. Once your Health reaches critical levels however, the suit reserves the last energy to your Health, hence the delay.

No...

How Stealth works is...Your suit energy is all being channeled to stealth. If you get shot, the damage goes directly to your Health, not to your suit energy. So even as you continue to die, the Suit still dedicates that energy to Stealth. Once your Health reaches critical levels however, the suit reserves the last energy to your Health, hence the delay.
wrong. getting hit in stealth mode immediately drains you suit energy.

when you are shot in cloak mode, the suit is supposed to change to armor mode because of the deflection feature

A) Suit is not automatic. Suit is not changing automatically to armor mode. It's manual. Cloak, armor, manually and ONLY manually changeable.
B) Getting bullet when you're in cloak mode breaks circuit of nano-disguise. So cloak is like damaged for some seconds and restoring, after restoring cloak devise suit is restoring energy.
Also Energy Devise getting damage when all energy drained with last electrical hit of last energy. Also for some seconds restoring and then restoring energy.
C) OP probably meet a cheater. Or that was some sort of lag.

happens to me alot

I noticed this yesterday more than before, but I've been seeing it some as well. I always pop out of cloak instantly when I'm shot, but I've hit people in the past who don't decloak for a few rounds (or if they are running, sometimes they just disappear and are still cloaked -- might have missed them, but some kill cams show them getting hit, turning and firing with armor up, and wasting me in 2 or 3 hits while I unload a clip in their face.. hmm).

The kill cam is pretty buggy, I'm guessing because of the time needed to load the video between clients.. but sometimes you can clearly tell hacking is being employed, and most often it's the no recoil hack or no spread hack (every bullet tracks exactly down to the dot on the sights).

The "good players" with the mild hacks are the biggest scum.. at least the "always cloaked" hackers and "one shot across the board" hackers are being honest/blatant about their slimy behavior.. the no recoil hackers and what I suspect are some "tap key to aim to" hackers are the more vile because they are trying to hide their cheating so they can abuse more people for longer.