First, some history...
The LT1 engine for MY94 was in the "first" part of GM's so-called "early roll-out" of OBD2 emissions controls. There were a few other GM platforms for MY94 that were also involved.
In 1994, the engine controls had partial OBD2 capibility in that some of the sensors and actuators were present along with some of the PCM programming. In MY94 any OBD2 DTC that occured was stored in memory but did not turn on the MIL. Back then, dealer service depts. were instructed to check any early roll-out car for OBD2 codes as a method of gathering information on how the system worked in the field. This gained GM some very valuable information in preparation for the official implementation of OBD2 in MY96
You cannot read OBD2 codes unless you have a Vetronix TECH1A, TECH2 or Mastertech.
The codes listed in this thread are not OBD2 codes.
You did the right thing by killing power to clear codes then road testing for 100 miles.
1 C12 means you have no fault codes stored for the CCM
4 H22 is the IP display version of PCM DTC22, a fault in the throttle position sensor (TPS). It's a history code which means it was not present when you read the ECM memory. That may be because you did that with the engine off. It is not indicative that the problem has gone away.
9 H64 is the IP display version of ABS/ASR DTC64 which is a TPS fault. Again, this is a history code that was not present when you took data.
Both of these DTCs require a TECH1 or equiv. scan tester and a factory service manual for the DIY to solve. Additionally, ASR DTC64 may require the Kent-Moore J39700 "Universal Breakout Box". If you have access that that equipment and are a DIY experienced in diagnostic work, you can fix the problem yourself. If you are going to use the DIY diagnostic approach, I suggest you use the scan tester to solve DTC22 first, clear codes, then road test. It is possible, if you fix DTC22, that may also solve the other code.
If you're not a DIY, you need a service facility experienced in GM diagnostics.
