When i am driving at about 38-45 mph, I sometimes feel like a shake or like the car is bogging. The car kind of feels like it is pushing its way forward or just kind of like a stutter pushing you forward. I do not know if that is something that is normal or what it could be? The car does not seem like its going to die or anything like that as if i accelerate past those speeds, it is great. It does not feel like that when accelerating through those speeds, only if cruising at those speeds. No shake in the steering wheel either.

 

When I had my sc400, i had a custom filter attached to the MAF. It turned out I experienced the same thing, around 40mph it would jolt and bog. I looked in my engine bay and noticed the air filter came off the housing we made for it. Put it back on, and all was well again.

 

well my air filter is connected well i think. i checked a couple of weeks ago, but i will check again

 

My car is doing the same thing....check all vac lines, see if you have a check engine light, tps, iacv, spark plugs, new cap and rotor, fuel rail, dirty throttle body, etc...process of elimination= $ which I don't have so I have to live with it for now. But this should be in the performance section

 

Is it auto? Seem to happen during a shift? Could be a solenoid problem... tps can sometimes act like that, but you'd most likely see more of the problem than just that one mph range your complaining of...

And check your transmission mount.....bad mount and the right speed/conditions the driveshaft can vibrate and shutter the whole car.

 

sound like a solenoid problem too me i had the same problem and it ended up being my transmission solenoid

 

have you washed your engine recently? might be spark plugs fouled up ,engine not firing all cylinders