Left the gas cap off...

after filling up after I got the Max back from the mechanic (replaced the Power steering pump) then I dove less than a few miles, saw it replaced it, parked it. Next day noticed it wasn't running smooth, it bogged down when I pushed on the gas. It did it once a day then every day then I couldn't drive it more than 50 ft!
I changed out the fuel filter & air filter & this helped alot but not completely.
I dumped some injector cleaner & gas additive (to remove water & stuff) and now when it happens I can floor it and it works it's way through the hesitation. Any ideas? I can't afford to take it back to the mechanic and I have no other vehicle to drive for a week. Please help!
Thanks in advance for any suggestions

Drain as much gas out of your tank as you can and replace it with some fresh gas. If that doesn't work then you need to check the plugs...if that doesn't work check the air flow. Most likely you have bad gas, however, if it isn't the gas then it's not firing correctly or isn't drawing the correct amount of air.

Thanks for the reply. I replaced the plugs and the cap & the rotor last night and that still didn't help. I am going to get at the ECU tommorrow & check the error codes that should tell me something.
How do I check the airflow?

Anything that will mess up your air flow that badly should give you a code when you start checking for them. I'd go ahead and check the codes to see if you get any response. It could be any number of sensors, so hopefully you'll get a read when you try it out. If you've replaced the gas, plugs, etc... then you've done about all you can do without checking for sensor problems. Any of the fuel injectors, air flow sensors, or any small sensor relating to firing can give you a stall, but regardless of which it is, if it's stalling that bad you should get a code back.