1996 Ford Bronco removing oxygen sensors- HELP!

I need to replace the front O2 sensors on my 1996 Bronco. All of my efforts have been unsuccessful in removing either sensor. First I tried PB rust penetrant and a 7/8 closed end wrench, no luck. Next, I purchased a special slotted socket, no luck. I tried an impact wrench, no luck! All of this I tried with pipes cold then I tried with them hot and re-applying the rust penetrant. The sensors wil not budge. If you have any advice on getting these boogers loose, please share your wisdom with me.