I posted this in the allison section, but this gets more exposure so I thought I would post it here. I have a 05 LLY motor with a 1000 series Allison behind it. Completely stock, no mods or tunes whatsoever. Here's an issue I've started to notice. I may not be explaining the most accurate way so bear with me:

If I have to get on the brakes really quick ( lets say someone stops quick in front of me to turn into a fast food drive at the last second), and I don't come to a complete stop (lets say I never get below 5mph) and I then accelerate to take back off, I've noticed it feels like the tranny doesn't feel like it is in the appropriate gear for a second or two and then it feels like it takes off. Almost like it's in limbo waiting for the tranny to go back into 1st gear before taking back off. If I come to a stop normally, my tranny will downshift back thru the gears. When I stop quick, I can't really tell if it does this, but I'm thinking it doesn't. I don't have any codes or lights on currently, but I'm wondering if this is a sign of worse things to come. Could this be a Torque Converter issue? Any ideas?

When you snub it down hard on the brakes, then hammer the power, the power will not come up until the transmission has decided which gear it wants, and shifts to that gear. Most 1000's that I have driven have that to varying degrees.
Same as during a regular shift, the TCM phones the ECM to cut the power (to about 60% I think) makes the shift, then phones back to turn up the power. Usually does that in parts of a second, but sometimes it is noticeable.
UNLESS... that is something that has gotten real bad in the last little while. Then check your trany fluid for level, color, and smell. Changing situations bother me more the the so called normal characteristics of the truck.

I have had somthing similiar happen, i dont think anything is wrong, like turnpike said, it sometimes has to think for a split second to come up with an answer so to speak, alot of people forget the allie is a very heavy duty tranny and it will at times have an "industrial" feel to it, unlike a normal truck or car, the only thing you could do if it gets on your nerves is have dealer check the tranny programming.

Sounds pretty normal to me also.

My truck does the same thing. Railroad crossings really produce the situation for this to happen.

X2 w/ turnpike. Remember, the Allison is not a luxury car transmission, nor is your truck meant to drive like a car. Give the fluid a once over, check and see if you have any leaks, and then try to be smoother with your throttle inputs after hard stops. Ease the power in and see how much smoother the truck will accelerate.

1 more thing to consider is if you have a larger than stock tire size. This will effect the shift points as seen by the tcm due to incorrect final drive ratio, causing the input speed to the VSS (your speedo) to be incorrect. Additionally, as "turnpike" had mentioned, the ecm defuels when shifts are made to safeguard the transmission from being overloaded under throttle. This will add to lag time created when less than desireable conditions are present during shifting events.

Turbo lag can also add to the sluggish feeling your getting.

RVC has good point also. If you get back on the throttle real quick and kinda hard, you might be feeling the lag.
Also some good responses in the Allison section.