I am having trouble with my 91 lumina 3.1. idles weird especially when cold. misses and hesitates. cleaned throttle body iac and new egr. cooling fans never ever come on, except when I do the paper clip to read the code thing. (OBD 1). I am getting codes 44 and 45 which are lean exhaust and rich exhaust respectively. how can I get both? is this an o2 sensor prob, or pcm prob? the codes seem to be opposites?? any help would be great, thanks Mike.