My car's a Tuning Nightmare!

Ok so my car is a tuning Nightmare.....I'm using a Tweecer R/t but it would still do it with a stock computer....If someone can help I'll be Greatly Appreciated....This is the deal....I have one knob position for a bone stock tune, nothing is changed except for loading the PRO M 24 file into it for my maf to work right.....The other tune is the same as that but is ran in open loop and has a few tweaks to the maf transfer (a little richer on the bottom end)....I can start it and it will be fine for a couple minutes then it will go PIG RICH or sometimes CRAZY LEAN out of Nowhere ......Rich as in 10 to 1 and Lean as in 20 to 1..(I have a wideband)...If I switch it to the other tune it will be fine, and eventually it will go Real rich or lean again so I have to switch to the other tune.... I'm really lost....I'm really getting the hang of tuning but it doesn't matter if the tune all of a sudden goes out of whack. I swapped the computer and maf out for my friends so I know they're not the problem. Last time I checked the ECT was working fine also...When it is really rich or lean if I go WOT it will clear up but will go back once I let off the gas.