Diagnosing Idle Issues
my 84 cucv 6.2 cranks but wont idle, as I push down the accelrator it revs up but the peddel has a slow reaction as I push it down it takes a few seconds to rev up.
Please consider the -20 TM for diagnosing your issues (there may be more than one). You may want to look at page 2-41 number 20 to start.
Some simple considerations. Idle speed is determined by a set screw on the side of the injection pump. As long as your pumps throttle can return freely to rest your truck will return to idle position. A binding throttle cable could prevent a return to idle which would result in a higher revving engine. But idle speed itself, everything else being OK, is controlled by that set screw.
Advice: don't mess with that set screw until you have ensured all is well based on the diagnostics in the TM.
Question: You say the pedal has a slow reaction. Does this mean it is hard to push down and takes a while to get it to depress? Or, is the symptom that the pedal depresses, but the engine is slow to respond to the change of throttle position?
You can manually rev the engine from under the hood to assist in diagnosis. Please be very careful as there are a number of dangerous rotating parts. If you pull up on the link where the throttle cable connects, gently, you can see whether or not the engine is slow to react as you described. Based on your symptoms, you may require an assistant you can trust to start the truck.
Please let us know what you discover.