87 pathfinder vg30i high idle and surging.
vg30i motor with 230,000 on it. its my second one. good rigs.. since the day i bought it always has surged when warming up. around 1,000-2,100, and after surging has hi idle around 1,300. now lately it has been doing it more when warmed up, and not in gear. other day it broke down on me. had to tow it. had spark, had fuel, seemed like some sort of sensor. checked the ecu. it threw a number 13 code. radiator sensor. then it started right up like nothing ever happend. ive checked for vacume leaks, cleaned the tbi. new wires, plugs, filters. also sometimes when its warmed up , and surging. ill turn the heater on and it will make it stop, and starts again when is turned off. i looked online, and have found some helpful info, but not what i need to know. if anyone can help me i would be very grateful. thanks