On Throttle/Off Throttle Stumble/Hesitation/Thing

[LikeUCare]

All, I have a 94 SS with a TD04 and TMIC and exhaust, nice running SS. It has its bugs but still a nice DD.

I am having an issue that I need help figuring out. If I accelerate (not WOT) and then I let off the gas around 3K because someone cuts me off or traffic checks up I have a stumble that I can feel in the engine/drivetrain and see as a bump on the Tach as it decelerates. This also occurs when I am cruising around 2K and touch the accelerator. There is a noticeable feel of what I call drivetrain slop. I have done the below to try to correct:

New transmission/motor mounts
Drivetrain inspected by two different mechanic/one being a transmission/axle guy
New pitchstop

I have no CEL, the car drive wonderful otherwise. Both mechanics suggest it is something mechanical/engine related but I have no idea where to begin. This car has 15K on a new rebuild and it did this before and after the rebuild.

Any suggestions? Wastegate sticking? Bad MAF? I am not seeing anything weird on my boost gauge except some boost flutter at WOT, otherwise I got nothing.

All ears, I have searched pretty extensively on the forum but haven't ran across anything close to this presentation.

[monkeyposeur]

I was having a funky hesitation problem until I replaced a cracked air intake from the throttle body to the turbo.

[LikeUCare]

You know, that isn't a bad thought, the path from turbo to TB is good, but I might have a leak between the MAF and turbo.

How would shaft play on the turbo present?

[Legacy777]

Does the stumble/hesitation feel any different between the acceleration & deceleration?

[LikeUCare]

Josh,

Sorry for the lag in response but no, it the same. 5K later it is still presenting the same as last post. Only thing different is the idle is starting to drop down really low and the car about dies on cold mornings when I let off the accelerator. I am thinking idle control valve for the later as the idle is a little more irregular even when warm.

But long answer short, it feels the same either getting on the throttle of lifting off. It is a little unnerving, I have tailored the way I drive the car to make it less noticeable.

[Legacy777]

Hmm....regarding the idle, have you checked for vacuum leaks and the normal stuff to check for? I suspect that if you find something related to the idle it may also be related to the hesitation. As for what that is....I unfortunately don't have any specific things to suggest other than the normal maintenance checks and such.

[cj91legss]

Get a can of starting fluid and start spraying every vacuum port and hose clamp, anything that has air going to it post maf and listen. if you come to a spot where your idle jumps up, you have a leak.

This is of course assuming you have not already done this.