My 1994 pathfinder is sputtering at 3000rpm when the engine gets up to temp refuses to go past 2000 some times

Could be numerous things. My advice is try nissan pathfinder off road association. Google npora and join the forum. They have helped me with 4 of my pathfinders.

cheers

Test engine coolant temperature sensor not registering a cold engine. this is a two wire sensor with a wire retainer holding connector on.

If the check engine light is not on, I doubt there is much you can do.
It sounds like one of the engine temp sensors or one of the other sensors. The engine temp sensor and the intake air temp sensor tell the computer what the outside air temp is and the coolant temp which allows the computer to regulate the amount of fuel going thru the injectors. Generally if one of the sensors has failed the check engine light should be on.
It could be low fuel pressure too.
You may have to have a shop check the sensors with a scanner and the fuel pressure with a gauge.

throttle position sensor or crank position sensor. but first have it on a fault diagnosis machine to find a fault code and go from there

The brake pedal issue is a lack of vacuum in the engine while not idling properly. There are quite a few reasons for this issue. I would have the engine codes read first to see if you have a fault code for any of the sensors. It could be any of the following, Map Sensor, TPS Sensor, O2 sensor, Temp Sensor, Fuel pressure regulator, Air intake Temp, fuel pump, broken wire, bad connection or a few other things.
Have the codes checked first to help rule out some of the more expensive items.

It is an integral rev limiter for park and neutral.

be very carefull if you are doing this yourself,it is critical to get the timing marks just right or you could do some serious damage to the engine.You must turn the engine by hand with a socket or spanner on the bottom pulley until the mark on it is lined up with the marker on the casing that surrounds it.Once this is done do the same with the top pulley,the mark on this may just be a small indentation that lines up with an arrow,once this is done you can then put on the belt and make sure it is tensioned properly.Once again,these settings are critical and if you are unsure DONT attempt it.

there isn't such a thing...there is a fuel level sensor in the gas tank and a engine temp sensor on the engine.

have your temp sensor checked and does any of your warning lights come on?

catalytic converter has started to break up blocking you exhaust.