The P1105 code is fairly common on these vehicles. There is a good article on how to test this here:
http://www.checkenginetroublecode.com/p ... ap-sensor/
I have replaced a few of what they describe as the "Baro Sensor" in the article due to sticking (I've always referred to it as the MAP/BARO solenoid valve). I would address this issue first as it can cause sluggish performance/lack of power.
Once that is done, I would check the ignition timing using a timing light. Warm up the engine and make sure the coolant gauge needle is around the middle (if it is too low, you may have a stuck open thermostat). Run the engine between 2000-3000 RPM for about two minutes. Let idle and turn off the engine. Unplug the harness connector on the throttle position sensor and re-start the engine. Rev the engine a few times and let idle. This will put the ECM into timing set mode. Check and adjust the timing, as necessary, with a timing light. Adjust the base idle to spec. Shut off the engine, plug the TPS back in and you're done. Hope this helps.