Cold Engine Idle problem

I have a question for the supra experts out there. I know that my fuel pressure regulator is not working it will not hold a vacuum. The stock one or the after market one (Cheap Ebay one). Therefore the car runs rich at idle, but at about full throttle at three thousand RPM's it leans itself out and misfires like crazy. I went to replace, but it was giving me the same problem before when it would idle then drop then go up then die. I put the old after market one back on, but it still did it. Then a few days later it stopped an ran again only with a set fuel pressure. Now though when it is cold the engine idles at 500 RPMs and the vacuum is real low, untill the car warms up then it is fine. Does anyone have any ideas on what the first problem is or the cold idle problem? I have been diagnosing it for a month and only found out the alternator was shorted out. If the non-working stock fuel pressure regulator is on along with a working aftermarket one will it cause the car to go crazy and how can i take the stock one off. Apparently there is only five stock fuel pressure regulators left in the country new that will work on the 7mgte so get one while you can. Thanks guys.