99 LTD: Shudder on accelleration at speed

[watersna]

99 LTD, Auto transmission, 4WD.

Lately I've noticed a kind of shudder, like repeated lurching, when accelerating under certain conditions:

Driving at highway speed (~65)
Slow down below ~50
Accelerate from ~50 to 65+

As I re-accelerate, I feel lurching around 55MPH then it settles down up past 60.

If I'm accelerating from a stop or from lower speed without decelerating first, it doesn't seem to happen.

Checked codes, showing nothing.
I also checked ATF. Level is fine and it is slightly brown but transparent

FWIW I just swapped springs and shocks to bilstein/OME with a 2" lift. Doesn't seem to me like that would have anything to do with it but figured I'd mention it.

Anyone have suggestions on what to look at next?

 

[spartacus]

99 LTD, Auto transmission, 4WD.

Lately I've noticed a kind of shudder, like repeated lurching, when accelerating under certain conditions:

Driving at highway speed (~65)
Slow down below ~50
Accelerate from ~50 to 65+

As I re-accelerate, I feel lurching around 55MPH then it settles down up past 60.

If I'm accelerating from a stop or from lower speed without decelerating first, it doesn't seem to happen.

Checked codes, showing nothing.
I also checked ATF. Level is fine and it is slightly brown but transparent

FWIW I just swapped springs and shocks to bilstein/OME with a 2" lift. Doesn't seem to me like that would have anything to do with it but figured I'd mention it.

Anyone have suggestions on what to look at next?

Take a look at your plugs if they are good. Could be dirty maf. If the maf is clean then a fuel issue, may be dirty injectors not keeping up.

 

[Bad Luck]

99 LTD, Auto transmission, 4WD.

Lately I've noticed a kind of shudder, like repeated lurching, when accelerating under certain conditions:

Driving at highway speed (~65)
Slow down below ~50
Accelerate from ~50 to 65+

As I re-accelerate, I feel lurching around 55MPH then it settles down up past 60.

If I'm accelerating from a stop or from lower speed without decelerating first, it doesn't seem to happen.

Checked codes, showing nothing.
I also checked ATF. Level is fine and it is slightly brown but transparent

FWIW I just swapped springs and shocks to bilstein/OME with a 2" lift. Doesn't seem to me like that would have anything to do with it but figured I'd mention it.

Anyone have suggestions on what to look at next?

Does it happen in a certain rpm range? Do the rpm's jump with the lurching?

 

[watersna]

Take a look at your plugs if they are good. Could be dirty maf. If the maf is clean then a fuel issue, may be dirty injectors not keeping up.

Cleaned the MAF sensor, replaced Air filter and spark plugs/wires today and haven't been able to replicate the issue so far, so it's looking like one of those was the fix. I'll take it out for some more in-depth testing tomorrow.

Thank you!

 

[watersna]

Does it happen in a certain rpm range? Do the rpm's jump with the lurching?

Looking like this is fixed but just for the record, it was at around 1500RPM