Toyota Repair: Refuses to accelerate, camary, toyota dealer

Question
We have a 1999 Camary. Occasionally, when we are accelerating away from a stop, the engine bogs down and refuses to rev.  More gas peddle does nothing to make it accelerate and the car creeps along with the engine almost stalling.  Eventually it accelerates normally after 5 or 10 seconds of jiggling the gas peddle.  My wife says it also will resume normal operation if she pulls the car over and waits for 5 or 10 seconds.  Alternately this sometimes happens, though less frequently.  When we are accelerating away from a stop, the engine revs a few thousand rpm (as per the tach) but the car does not accelerate.  It seems like it is not in gear and coasts to a stop.  This too self-corrects after about 5 or 10 seconds.  Six months ago we had the transmission rebuilt to fix this latter problem -- which did seem to be fixed and did not recur until this week.  The first problem (where the engine bogs down and almost stalls), however, is completely new.  While these problems are different, the net effect is the same -- the car does not accelerate -- and we are experiencing them both this week and that is new.  The car has been fine for months before this.  We just took the car to our regular mechanic and he replaced the gas filter but it did not solve the problem.  We then left the car with the local Toyota dealer for three days, and while they experienced the first problem (so they know we are not crazy), there were no engine codes and they could not diagnose the problem(s).  They returned the car to us unrepaired -- and, of course, it acted up again as my wife drove it home, virtually stopping in the middle of the street as she tried to accelerate.  Any help would be appreciated. The way it is, this nice car is not worth driving. Thanks!

Answer
I think that you need to take it back to the toyota dealer and have one of the service techs go for a test drive with you to demonstrate the problem, this seems to be a safety issue, getting stuck in the middle of an intersection can be dangerous and unsafe, I'm not going to recommend any course of action because I would be guessing as to what the problem may be,I know you said that they experienced the problem but why did they not make a recommendation what is needed to fix it?