1992 Ford Tempo Intake Air Temperatue Sensor

Ok Ive Got 92 ford tempo GL That Seem's To Be A Fuel Guzzler Which It Wasn't Before, Ive Changed The Air Filter, Intake Air Temperatue Sensor, Mass Air Flow Sensor, Throttle Position Sensor, Air Control Solenod, & What Im Trying To Say By Fuel Guzzler Is If Im Doing The Average 100Kmh Speed Limit Down The Road My Rpm Sticks To 3000 Rpm, The Vehicle Idles Fine At 800 Rpm In Park, But When I Put In Drive Hold Down The Brake Still Idles Fine At 800 Rpm, But Once I Start Rolling Down The Road The Faster I Go The Rpm Stays Higher Than Normal, Like Another Example Im Testing At 120 Kmh & My Rpm Sticks To 4000 Rpm, I've Checked The Engine Codes Both Key On & Running, While Running Codes Came Up With (111 System Checks Ok) & With Key On I Came Up With Codes (112 - Intake Air Temperatue Sensor Is / Was Low Or Grounded) & (212 - Ignition Tach Signal Was Erratic (Module / Wiring) Or Spout Circuit Fault - Ignition Systems) Im Still Not To Sure What 212 Means, But All I Know Whatever Feeds 112 Isn't Doing It's Job?