I've noticed a problem that has seemed to get worse over time now.
When decelerating, say down a hill or just slowing down, the car will start hesitating...almost like the throttle body wont close all the way for a moment then it'll close completely all the sudden.

It only happens at lower RPMs in 2nd or 3rd and it especially happens when cruise control is on.

I checked the throttle body and there was a significant amount of blowby in it as well as the intake mani...I cleaned it all but still no change.

I installed a catch can for the blowby.
Perhaps I just need to buy a new tb?
Ideas?

 

I think what you are experiencing may be normal. I believe the condition is made worse by worn engine mounts.

My car has done this for a while now and the condition has never caused me to be concerned about the engine. The cruise control system will actively try to keep your speed at the set level when going down a hill, if the hill is steep enough the ECM may pull all power to maximize engine braking. My mounts are very worn because I have several vehicles and I haven't been motivated enough to swap in the poly mounts I bought a couple years ago. I'm my case the extra engine movement from the bad mounts makes the transition to engine braking far more noticeable.

I might help to know the year and mileage of your vehicle. Depending on miles, if your engine mounts are old I would suggest starting there as the symptoms getting "worse over time" could be matching the degradation of the mounts.

 

If you have the A/C on your rpm is getting too low to keep the compressor going and it is adding throttle and fuel to raise rpm. If your rpm is in the 1200 range or lower it is trying to maintain idle and switching from idle to fuel cut off deceleration ... downshift and raise the engine rpm!

 

Thanks for your input.
I'll check the motor mounts.
Car is only at 50k so I hope they're not going bad yet! hah