Car was hesitating. Was Advised to Clean out the Throttle body. I cleaned it with Throttle body cleaner. Replaced the ICM and the IAC Internall to the IAC everything looked great. I re-install the throttle Body and get way high RPM’s . Adjust the IAC still reving high. at the lowest setting I get pulsing Idle. Vacuum Line? Reversed Cooling Lines under the Throttle body?
Could be a leaky gasket or cracked vacuum line.
Did you replace every gasket you disturbed?
Everything non-metal you touch is suspect on a 26 y.o. car.
Spray carb cleaner or point an unlit propane torch at things while listening for a change in idle.