Have done a search but haven't come across anything that describes my problem exactly, so i'll put it out here.

I have a 99 th advance wagon, 3.5L auto. I suppose the problem i have could be called surging, it only happens under acceleration, say you are under slight, constant throttle up a slight hill, the accelaration will vary even though the revs are climbing steadily and your foot position on the throttle isn't changing, it was very noticable a while back when i had a hole in the exhaust as the engine note would change as it happened, it's like i'm pressing the accelarator harder for about half a second, then lifting off a bit, then pressing down again, and so forth, but my foot isn't moving on the throttle, feels like the car is just changing the fuel mixture on its own for no reason, it also feels very sluggish under 3.2Krpm, with a noticable shove in the back as soon as it hits these rpm, any ideas on the cause? normal service items are ok, so i' thinking more along the lines of tps, injectors, fuel pressure, ecu ect ect. anyone experienced the same and had it repaired?

I had this problem or something similar check your fuel pressure, your vacuum hoses, and fuel lines. hope this helps.