When I got my car, exact same as yours, I had the same problems when I bought it.
My car runs smooth now. Pretty much one thing led to another, and it had to be fixed.
The trigger: the VSS (vehicle speed sensor). It crapped out, leaving my speedometer at 0. I came here, and I found the prob. Fixed it, replaced the ATF, but I found that it was still shifting bad, and it wouldn't go into OD.
I was told to check the TSS (turbine speed sensor, torque converter, I believe). The sensor was disconnected, so I reconnedted it, and it works flawlessly. The car drives better than it did going off the lot!
BTW, I also did the headlight fix, and it's coming out nicely. I can actually SEE at night.
Now, back to your problem. I would check the ATF. If it's not red, replace it (mine was brown, cooked immaculate). And it might be low when you check it. Fill it to the normal level. It'll help a lot. I assume your speedometer is working, so no need to worry about the VSS (but if it does go, you'll know what it is).
Double check the TSS. You can easily check this by turning the steering wheel all the way to the left, and looking into the driver-side front wheel well. You'll easily make it out. MAKE SURE IT IS CONNECTED. We disconnected it when looking for and replacing the VSS (hey, curiosity killed the Contour).
If none of that helps, then it may be something more. Still check for codes again.
