Ok, so over the last few weeks Im going along just fine about 40mph and all of a sudden it seems like im bogging down and if I give it a little gas or let it be for a few seconds it gets up and goes again until I slow down and downshift and give it a little gas in 2nd or 3 gear, it does it all over again, I have done cap, rotor, plugs, wires, fuel filter, fuel injector cleaner and Im starting to think that it might be my clutch or tranny, but my rpms stay the same when it happens and it only does it after the car warms up, Im at a big time loss here please help! 97 DX 140000 miles.

 

maybe iavc or fit valve .my car did the samething