98 Wragler Check Engine, missing out

I am new to the forum. I have a 98 Jeep Wrangler, which I bought new in 98. It currently has 111,000 miles on it. Yesterday, I noticed the Check Engine and Airbag lights come on, However, the airbag light has now gone off. The next time I tried to start the Jeep, it had a hard time starting. I took it to Auto Zone this morning, and they ran a Diagnostic on it, and the Check Engine Light was for P0123 (Throttle Position Sensor Voltage Too High). I disconnected the battery while I installed the new Sensor, and once completed I hooked the battery back up. The Check Engine Light is still on, and the jeep still is missing out. I do have an exhaust leak on my header, which I have an appointment to replace next week. Also I did fill up the previous day, and I am currently at about 1/2 tank. I did put in some heet (fuel treatment), and some fuel injector cleaner (STP), and it appeared to help some, but still missing out. Any Ideas????

If the problem started suddenly after your fill-up, I'd avoid that gas station!

However if it was occurring prior to that, I'd suspect the crankshaft position sensor or the camshaft position sensor.

Not sure, but think I found the problem. The vaccuum line for the HVAC system, was pulled off of a nipple, which is on the Intake manifold. No problems since connecting it back on (knock on wood). This might also explain the Throttle Position Sensor code, since vac leak would mess with that sensor's job (controlling the air butterfly on the throttle body).