Car: 2006 Mazda3 2.3 hatchback, ~43K miles, no problems at all up until now, regularly serviced and checked at the Mazda dealer every 3-5K.

Problem: 2 weeks ago, as I was pulling out from my house in 1st gear, had a sudden loss of power. Engine didn't respond to the accelerator pedal almost at all, had to floor it to get it to 2K RPM. Turned off car, restarted and everything was fine. CEL came on, but eventually turned off. This happened 2 more times over the following week.
Local Mazda dealer diagnosed it as a short in my throttle body. As a naive loyal customer, I had it replaced for $900. Car ran fine for a day and then the problem recurred and CEL came on again.
Dealer now diagnosed it as a problem with the accelerator pedal potentiometer. Clearly, I was very wary now, since the last time didn't fix it and wanted it diagnosed and fixed for free. After negotiating and clearly failing, I ended up paying another $230 for a pedal assembly.

Car ran great for 3 days and now had the same problem, except it occurred while I was driving in 3rd gear. Clearly not going back to my dealer, since I don't think they ever fixed the main problem, but I am out of luck. Some posts suggest checking the mass airflow sensor or the EGR, etc.

anyone have any thoughts on this? I love the car, but now am very wary of driving it.

 

It's more than a bit difficult to diagnose this type of thing over the internet; sounds like it's time for you to find a competent independent mechanic.

With the above said, it sounds like it's also time for you to file a small claims action against your dealer; clearly they're incompetent.

 

I had a simliar problem w/mine twice.
The first time it was a faulty MAF sensor and covered under warranty.
The second time the symptoms were the same but it was a little check valve in the closed fuel evaporative system. It's located in a long hose in the middle of the engine compartment close to cyl #4. I am told that sometimes if you take the handle of a screwdriver and rap on the valve, it will free up.
Me? I wasn't so lucky. The dealer charged me $360 the day after Christmas, $100 to diagnose, $180 for the part (a hose w/a plastic check valve in it that clearly costs about $1.50 to make) and "shop supplies" (WHAT shop supplies?,) and the rest in labor.