GTA4 Online (PS3)- Why am I dying in one hit?

[CASE]

I've been playing for weeks now, and it seems that no matter how much ammo I unload, and no matter how much health and/or armor I have, I ALWAYS die in one hit! Is this a glitch, is something wrong with my PS3? Or is there some secret to killing everyone in one hit regardless of distance, weapon, or auto-aim/manual aim? What is going on???

 

[Kourosh]

Use these Cheats
Phone number cheats:
Press up to access the cell phone. Press up again to access the keypad. Unlock the following cheats by dialing the corresponding numbers:

Climate Change - HOT-555-0100
Full Armor & Health - 362-555-0100
Full Armor/Health/Ammo & Fix Damaged Car - 482-555-0100
Identify Songs on the Radio - 948-555-0100
Raise Wanted Level - 267-555-0150
Remove Wanted Level - 267-555-0100
Spawn Annihilator Police Helicopter - 359-555-0100
Spawn Burrito - 2826-555-0150
Spawn Cognoscenti - 227-555-0142
Spawn Comet - 227-555-0175
Spawn Double T - 245-555-0125
Spawn FBI buffalo - 227-555-0100
Spawn Gaucho - 245-555-0199
Spawn Hex er - 245-555-0150
Spawn Innovation - 245-555-0100
Spawn Jet max - 938-555-0100
Spawn NRG-900 - 625-555-0100
Spawn Police Chopper - FLY-555-0100
Spawn Sanchez - 625-555-0150
Spawn Slam van - 826-555-0100
Spawn Truism - 227-555-0147
Spawn Super GT - 227-555-0168
Weapon Package #1 - 486-555-0150
Weapon Package - 486-555-0100

Gang wars unlock ables:
Unlock the following weapons by completing the corresponding number of gang wars:

Assault shotgun in safe house - Complete 40 gang wars.
Automatic pistol in safe house - Complete 20 gang wars.
Carbine Rifle in safe house - Complete 30 gang wars.
Grenade launcher in safe house - Complete 50 gang wars.
Sawed-off shotgun in safe house - Complete 10 gang wars.

Achievements:
Unlock the following achievements by completing the corresponding tasks:

Easy Rider achievement (100) - Finish the story.
Full Chat achievement (70) - Build terry and clay's toughness to 100%.
Get Good Wood achievement (50) - In the bike races, whack off 69 bikers with a bat.
One Per center achievement (5) - Help billy get his bike back.
The Lost Boy achievement (25) - Become leader of The lost.

Hookah bike from clay:
Unlock the following bikes by performing the corresponding tasks:

Bait 800 - Complete all of angus's bike theft missions.
Hookah - Beat 12 races in single player mode.
Innovation - Kill all 50 seagulls.

Un lockable vehicles:
Unlock the following vehicles by performing the corresponding tasks:

Annihilator Helicopter - Kill all 200 pigeons.
Raster Color Huntley SUV - Complete 10 package delivery missions.

Friendship bonuses:

Alex at 80% - gives you a discount at clothing stores for 24 hours.
Brucie at 90% - flays his helicopter to you.
Carmen at 75% - replenishes your health.
Dwayne at 60% - ships you a car full of gangsters who will protect you.
Kike at 75% - clears your wanted level (when out of missions and under two stars).
Little Jacob at 60% - ships you a car full of guns which you can purchase.
Packer at 75% - makes you a car bomb.
Roman at 60% - sends a taxi for you to drive throughout Liberty City.
Stevie - Complete all 30 of his vehicle thefts. The south Behan garage will then give you more money for each vehicle that you deliver.

Resurrect dead cars:
Call 911 on your cell phone and hang up when they pick up.

Happy statue easter egg:
Navigate to the statue of happiness on happiness island by way of helicopter. Have the helicopter set you down on the very top of the statue. You'll see a sign up there that says "No Hidden Content Beyond This Point". If you head inside of the statue from this point, you'll see an actual beating heart inside the statue.

Fire truck water cannon:
Steal a fire truck, and push the fire button while driving. This will fire the super-powerful water cannon.

Crank calls:
Dial the phone numbers written in odd places, such as on the side of a building. You can crank call someone on the other end.

Get GTA3 outfit:
When you have to decide whether to kill dwayne or playboy X, kill playboy x. You can use his loft and change clothes there.

Reveal item locations at internet cafe:
Log into a computer at TW@ Internet Cafe and go to www.whattheydonotwantyoutoknow.com to view map locations of all weapons, health, armor, vehicles, pigeons, ramp/stunt, and entertainment.

Free taxi ride:
Just before you reach your destination hold L1 to smash the window and scare the taxi driver away. You must have a gun equipped in order to do this.

Change police siren sound:
While driving in a LC PD cruiser press the left-analog stick.

Erase wanted level:
Do any one of the following to erase your wanted level:

1. Enter any mission marker(not date markers).
2. While in a police vehicle, activate any of the vigilante or most wanted missions.
3. Call a friend from outside of the radar zone.

Gun shop hint:
After killing the owner of the gun shop you can shop there again if you change clothes.

Lower wanted level:
To lower your wanted level, start a mission or enter a safe house and save the game.

Tug boat:
There is a tug boat located between Alden and the industrial island in front of two barges. You will need another boat to get to it. Once near it, jump on it and hit the enter vehicle button. You can just cruise from