Toyota Repair: Toyota Camry 1992 V6 Emission Problem, toyota camry 1992, air fuel mixture

Question
My Toyota Camry 1992 V6 Did not pass the smog check. I retrieved a codes 25 & 26 and Haynes repair manual says fix the running rich but it doesnt say what particular component to fix. Could you elaborate how to fix a running rich problem? I really appreciate your expert advice on this matter. Thank you very much.

Answer
These codes are caused by a rich-lean condition, it alternates between too rich and too lean, most of the time this happens because there is an engine misfire that causes a lean condition, the computer then tries to compensate for the lean run and richens the air fuel mixture up until it's too rich again and the cycle continues then it turns the check engine light on.
The codes could be triggered in several ways:
An engine misfire
An intake system leak
A misfire caused by a leaking valve
A misfire caused by a blown headgasket
A misfire caused by a bad spark plug, plug wires etc.
These are the basic things to check, make sure that the basic engine functions are correct, it may be a good idea to have the engine compression checked before replacing a lot of parts.