You must consult a factory service manual or a reputable repair manual specific to your 1988 Mustang 2.3L engine. These manuals will provide the proper torque sequence and specifications for each stage of the tightening process. Using incorrect torque values can lead to serious engine damage.
Trying to find this information online without a specific manual is risky because different sources may give conflicting and incorrect information. Invest in a proper manual – it's a worthwhile investment to protect your engine.