88 Ranger 2.9 idles high and low

IASC valve

Idle Air speed Control valve, its on the side of the intake right behind the throttle body, passengers side, about 1.5 in diameter and 3 long

shut the engine off, block the throttle wide open, remove the intake hose completely from the truck

get a can of AutoZone's best el-cheapo carb cleaner, and spray the hell out of the throttle blades and the two small air passages, one in front of and one behind the blades

let all the excess evaporate, unblock the throttle

take the hose and bang the loving bejesus out of it against a pole or door frame, knock all the cumulated crap loose and blow it out with air

put hose back on

start engine, you will have to hold throttle about half open to clear the fumes from the carb cleaner, it may take 30 seconds or longer till it starts

if that doesn't fix it, replace the IASC valve

Will this work on my '89 ranger 2.3l 4 cyclinder with no distrib or carb?

no idea

my experience with rangers is with 2.9's