I hope you don't mind if I jump into this discussion but I'm new to this forum, have pulled OBD-I codes from my 94 Ranger (2.3L), and this is a close match to my situation. I got "335" as the first OBD-I code, and it's not even listed in my Chilton's manual.

My symptoms are--rough idling and recently a change in sound of car--almost a fast sputtering sound--not too unlike the OLD VB Beetles used to sound when they accelerated. It's most noticable during acceleration and I'm thinking some type of vaccum leak may be occurring.

I did a search in this forum and this thread came up. I pulled up the link (www.niehoff.com.....) that "96_4wdr" provided. My symptoms are different than those described.

But I guess I have a couple of questions:

1) Where is a COMPREHENSIVE list of OBD-I codes for my car? I can't seem to find one online.
2) How should I attack the codes. I get : "335" (then 335 repeats once more), then long pause and separation--indicating next codes are "continuous memory codes" according to my manual. Then "172" (then 172 repeats once). I don't know how to tell if "335" code is a "KOEO" or "KOER" as indicated by "projectSHO89" in his comments above. Furthermore, I don't know the "diagnostic procedure" for each code type, as he indicated.

Any help would be much appreciated....
Gary