can bad o2 sensors cause a power lose i just recenly had a exhaust manifold leak whitch i just fixed but my car has lost its power. before the leak i could esaily spin my tires in secound now its just nothing. i donno whats going on. also what about o2 simulators whats the pros and cons of them

 

Here's what happened to my 99 pick up. Had a collector leak that got real bad during a long trip towing a car carrier. During the trip, the SES light tripped due to efficiency of the cats. Here's what happened. The exhaust leak caused the front O2's to see a lean condition. The PCM richened up the mixture so much, the cats were destroyed. That is they got plugged up. Now I had no performance. So what to do. Priced the cats which are 2 welded to a flange and cost well over $500.

So we gut them and of course the same SES trip for inefficient cats. That is where the simulators come in. The front O2's are used for engine management. The rear O2's are used for keeping an eye on the cats. The back O2's are the ones that get simulated, not the fronts. With a simulator, you can get rid of the cats and get rid the SES light too. I bumped into a thread the other day about these simulators.
http://www.o2simulator.com/

I've checked the output of the simulator with my Vantage and it works great. I have not installed them yet but will today. It will be a few days before I know if it worked so Email me and I'll reply on the weekend with the results.

Dave