What causes when i stsrt my truck and my fingers slip off the key or i dont let it crank long enough when i let go of the key and start it again it will not start?

you need an ignition switch. One way to figure it out is to turn the key to engage the starter, quickly........over and over, the "catch and start" will happen with no change and suddenly, its engaged. Or, keep the key in the START position, don't let up on it and hit the steering column with your fist, or the steering wheel. It may just be shorting out.

Maybe the battery is not giving enough amperage to crank the engine

Yes, it can be a fuse. Check the 15amp INJ1 fuse under the hood. Also check the IGN 0, PCM 1 and PCM B fuses.

If you have low compression you have only a few things that cause that. 1. you have a blown head gasket. 2. you have a cracked head. 3. your piston rings are shot. With a no start condition I can almost garuntee you have either number 1. or 2. If you wanna check the crank sensor, have someone spin the motor while you pull off a spark plug boot. If you hear/see it firing then the crank sensor is good. Crank sensors either work or they dont. If the crank sensor is bad, you will lose fuel and fire.

i would check battery connections and test battery. a battery can have a bad cell and run lights but not have enough amps to spin a stater. if everything on battery is good i would suspect a bad starter

First you must determine is the engine is cranking and not starting or not cranking. If it is cranking, determine if it is cranking fast enough. If not, it could be due to the starter drawing too many amps or the battery is not strong enough to support the cranking amps. Once you have determined the cranking speed to be sufficient, see if spark is being delivered to the cylinders. If no spark, trouble shoot the ignition system. This should give you a start in determing the problem. If all is well up to this point, check to be sure fuel is being delivered to the cylinders via the injectors. If no fuel is getting to the injectors, perform a simple fuel pump operation test by turning the ignition to the off position and keepingt it in the off position for approximately one minute. Next turn the ignition to the on possition and listen for the operation of the fuel pump (which is in the fuel tank); you will hear the pump ticking for a few seconds until the pump pressure buids up then the pump will stop ticking.

if it is a 2.2 you have a tensioner belt take a 3/8 rachet from in the engine compartment towards the firewall on the passenger side look under the power steering pump there should be a dog leg type with spring follow down shaft you see a square hole in it put the rachett head in hole the square end now pry up or down so it moves your belt will loosen now hold the rachett tight not to slip and remove the vbelt to install do the same if you need someone to help its ok because it is a tight place but dont put your fingers in the belt groove because if the rachett slips you could loose a finger as well make a drawing on a piece of paper before removing sometimes you will forget how it goes or the belt doesnt fit and you have to get another one and you dont remember how it goes on example start crank pulley to idler pulley to water pump to alternator to tensioner and so on this is an example dont follow it do your own drawing

will the engine crank when you turn the key, and will not start or does nothing happen when key is turned on. If nothing happens when you turn the key, you may have an dead battery. if it will crank and not start, may not be getting fuel or the engine isnt fireing. Check fuel first, then check to see if it the spark plugs are getting fire.

Can be a key problem. If it is not working right, it will disconnect the fuelpump as a safety-measure to prevent stealing your car. (only if it's a key with a chip inside)
Sometimes you can reset your key at the dealer. And please check your battery that's inside your key.

ANY TIME SECURITY LIGHT COME ON YOU HAVE FAULT IN THE IGNITION KEY OR KEYS THEY COULD BE WORN OUT WHERE TO A POINT WHERE THE BCM AND PCM DONT RECOGNIZE THE CAR KEYS CAUSING NO START CONDITIONS.ALSO WORN KEY SWITCH AND BCM WILL CAUSE NO START CONDITIONS.TRY THESE TWO THINGS TRY ANOTHER CAR KEY IF STILL DONT CRANK.PUT KEY IN IGNITION TURN KEY TO ON POSITION WITH ENGINE OFF LEAVE KEY ON POSITION IN IGNITION FOR 10 MINUTES WATCH DASH SECURITY LIGHT WHEN IT TURNS OFF IN 10 MINUTES.TURN OFF IGNITION FOR 5 SECONDS THEN TRY STARTING CAR IF CRANKS OR DONT STILL THE PROBLEM IS IN THE THEFT SECURITY SYSTEM NEED TO GET DEALERSHIP TO FIX THEY HAVE DIAGNOSTIC EQUIPMENT TO FIX AND REPROGRAM THEFT SECURITY. SYSTEM.