My 88 350 has been getting a code 45 for a while now. I replaced the O2 sensor a while ago and that still didn't fix and ive been looking around and will try to adjust the IAC tomorrow and install my TB coolant bypass and hopefully that might fix the problem. but if that doesn't do it any other ideas of how i might fix it?

 

helm manual. not being a jerk but in the helm book it gives a path of things to do so you can diagnose the issue.
a hayes book has a fraction of hte info the helm has for your car. the helm book is the size of 2 hayes books.