1995 Toyota Camry Pressure in engine

Car runs fine but gives me weired problem when I get stuck in traffic where I have to push brack then accelerate maybe 1000 times. Problem: while stuck in traffic all of a sudden after a while I notice pressue builds up in engine and it gets difficult to push brake. If I release brake car wants to go very fast. I put it in neautral or parking rpm shoots to 6/7000. Obviously I can't stop or don't want to stop on the bridge that's the problem happens where there's a lot of traffic. Once I cross the bridge when I want to stop, it becomes extremely hard to stop the car as I push the brake and also hand break but it still slowly moves howver it does come to a stop then I turn the engine off. When I open the hood I notice water/anti freeze leakage like the car has been heat up which is not true, I beleive this is because of the pressure that had been built up then I wait few minutes for it to cool down then start the car and it drives fine and rpm is normal. What could be the problem?