Hoki What happens is the choke is engaged when it first starts and the mixture is enriched for a short while. Then as the KEY is on and electricity goes to the choke heater the choke slowly opens and the regular lean mixture comes into play. If the idle jets are clogged or the TUBES in the throttle body are stopped up... You get a little less to none at all gasoline in the engine at idle.
This small bit of gasoline is counted for when the hi-speed jets are installed...i.e. the engine COUNTS on the idle amount of gasoline at all speeds! So a carb in your (possibly) condition is running too lean at all speeds.
If that is the problem then it needs to be corrected.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />