Took truck in for an Emissions and Safety Inspection except it failed the pollutant HC(ppm) Emission Test at High Speed the given standard is 143 and the current reading topped out at 196 but only at the Higher speed (25mph) at the lower speed it read out from Standard 147, and the reading was 85. It passed all other Emissions pollutants tests. I would conclude a simple tune up is needed or what else could cause the problem?

seems like those may be two different issues. check for vacuum leaks and have your fuel psi checked. High fuel pressure can change your emissions numbers. I believe the fuel psi should be 30-45 psi. if its way above that then the nest step is to check the fuel pressure regulator

Use Google & study Vehicle Exhaust Emission
You'll be there for weeks,if you even understand it all
Could type in: High HC Exhaust Emissions or vehicle
hydro carbon problems
When a vehicle gets that old your close to mechanical
issues that aren't worth fixing

Emission test by codes reader? or smog? Any codes?

Any codes? any problem tune up, catalytic convener, burning oil.

fist i would like you to post the year make and model of the truck along with the HC ppms and NOX ppm it would be very helpful but high hc and nox can be attributed to a faulty EGR system nox is produced when the combustion chamber temperature gets too high so a small amount of exhaust is cycled back into the air stream to help cool them there are other causes but without looking at the levels its much harder to say

run the fault codes to find the faulty sensor
sensors that control the exhaust emissions are the HO2S ( heated oxygen sensors in the exhaust manifold/s
the O2 sensor ( oxygen sensors after the cat converters ) and the EGR unit that recycles exhaust gas back through the engine to re-burn the gasses

First either replace or clean the idle air control valve.You can clean it with a non-chlronated brake cleaner and wire brush.Then take the mass air flow sensor off and do the same but don't use a brush just the cleaner only.

Jose, I don't know if this will give you the answer you are looking for because there are many things to consider here. The exhaust gas recirculation valve (EGR) is one of the main things involved in reducing NO emissions. This valve is controled by the power control module. (PCM) This is your vehicles computer. The PCM monitors the vehicles speed and will command the EGR to open when the vehicle attains a certain speed, which is why the ASM test being done is recorded at two different speeds. At 25 MPH your vehicle failed the hydrocarbon (HC) emissions limit and this could be for a number of reasons. When is the last time you car was tuned up? Old spark plugs, wires, clogged air filters, oxygen sensors, leaking injectors (personal experience) or the PCV valve could be contributing to the results of the test. I guess that the easiest way to go is to tune up the engine replacing the spark plugs, wires, air filter and the PCV valve and don't forget to have the oil changed at the same time. Only then should have the vehicle retested and see what the results are. Should it fail again you may have to consider having the EGR or the catalytic converter replaced depending on what portion of the test fails. If the NO fails I would consider the EGR. If the HC fails then I would consider the catalytic converter. Good luck with this.

means that the hc,co2,nox, emissions are too high, you will need the numbers in ppm on the read out to begin diagnossis

possible but could be head gasket or valves , or worn rings and is by passing the pistons going straight out the end ...or maby settings are wrong ? try carb cleaner and inspect visually air-filter etc.