Engine Performance problem
1995 Mercury Sable 6 cyl Front Wheel Drive Automatic 168000 miles
After I have been driving for 15 minutes and I come to a complete stop, it has no power on take off, rev's high, then there is a wicked jolt/kick and then it picks up again and drives OK until I come to another stop, the engine light comes on as well, there is also a very small leak (not sure what it is) but it is in the front, middle practically right underneath my front bumper. I have also smelled something funny coming from driver's front end side smells almost like rubber burning (not gas, not rotten eggs) it passed emmissions and has had a tune up, thermostate has also been replaced. I was told it could be a sensor, I am stumped, any suggestions?