1988 Chevy S-10 explain in detail please computer ground

I just noticed that?
You need to stay in one post and do not write new post every time
just hit replay to question
only way we can keep up with what is you are trying to do

the( ECM /PCM /Computer )job is to ground the injector and its a circuit board
and not a serviceable unit
check the TPS volts

Does TPS stand for throttl position sensor?

Yes TPS is the throttle position sensor
see if its volts high then the computer will shut down the injector
this is what was called a flood mode

What should the TPS read? If it is to high what should I do?

Im sure you know this, but just in case there are two blk/white system ground wires coming out of the computer at pinouts A12 and D1. This is the only grounds you can check.

TPS volts should be under 1 volts
and as u step on the gas the volts should start to increase
if it volts high at idle disconnect the TPS and try it, crank, check if u get injector pulse
and if u have it then I would say replace the TPS
good luck

When the fuel injectors pulse but right now that are not still trying to figure it out. When the ignition is on do they have voltage? If so what is it? When they do pulsate are they supose to be less than a volt?

When key on
you should have a battery volts at one of the injector wires
and when cranking the computer should pulse ground the other wire causing the injector to pulse on of f
remove the injector plug wire and stick a noid light in crank the engine does it flash
if all ok it should
and then check your fuel pump and fuel pressure

Dose the timing have to be dead on, or can it be off alittle bit and still start.

The timing has to be on

The destribiter, dose it have to be dead on at tdc.

As a helper cranking the engine u can turn the distributor left and right a bit
see if that help
if the distributor of a bit it should try to start but if a lot no

What should I do if that don't start the truck
should I take the destribiter out and try retiming it

I wouldn't take the distributor out just for trying
rotating the distributor left and right should compensate for any timing of if any
if not then you are looking in the wrong area
and or timing chain is out of timing

How do you change it from 2wheel to four wheel high & low
do you put it in park or put it nutral
do you back up in between changing from 2 & 4H&4L

Neutral
brakes on
shift to 4 low

No. One at tdc, what is the location of the destribitor, show picture