2005 Suburban Trans/TPS HELP

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I have an '05 Suburban Z71 pkg. It has a chatter that I am trying to "guess" at what is causing it. Thought I would ask if anyone else was having this issue. Around 1500-2000rpm there is a chatter that sort of makes the truck shake. It has happened at different speeds but usually around that rpm range. Now, the other thing is that it may have to do with the actual position of the accelerator. When the chatter happens, if I let off the gas pedal or give it more the chatter goes away. So, I don't know if it is a transmission issue or if it is a Throttle Position Sensor issue. I did play around with the 4x4 buttons one time and that seemed to make it go away for a little while, but doing it again has made no difference. It usually does it going up a hill though it will do it on flat roads too. I bought this vehicle used about a month ago and my wife says she didn't notice it doing this until after I tested whether or not it would go into 4x4 mode. Didn't do any off-roading at that time just made sure it shifted. Anyone got a guess from that description or maybe more quesitons that I can add information to for troubleshooting? A second question is, while running down the road at say 30mph, 60 mph and 70-75 mph could someone tell me what your oil pressure gauge reads? Mine is about middle(40psi), then nearing 60psi or slightly over for the other two speeds. I do have oil in there and it is "full", not running low or too full. Sorry I was so long winded, wanted to give as much background for the help I need.
Thanks,
Marc

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I have an '05 Suburban Z71 pkg. It has a chatter that I am trying to "guess" at what is causing it. Thought I would ask if anyone else was having this issue. Around 1500-2000rpm there is a chatter that sort of makes the truck shake. It has happened at different speeds but usually around that rpm range. Now, the other thing is that it may have to do with the actual position of the accelerator. When the chatter happens, if I let off the gas pedal or give it more the chatter goes away. So, I don't know if it is a transmission issue or if it is a Throttle Position Sensor issue. I did play around with the 4x4 buttons one time and that seemed to make it go away for a little while, but doing it again has made no difference. It usually does it going up a hill though it will do it on flat roads too. I bought this vehicle used about a month ago and my wife says she didn't notice it doing this until after I tested whether or not it would go into 4x4 mode. Didn't do any off-roading at that time just made sure it shifted. Anyone got a guess from that description or maybe more quesitons that I can add information to for troubleshooting? A second question is, while running down the road at say 30mph, 60 mph and 70-75 mph could someone tell me what your oil pressure gauge reads? Mine is about middle(40psi), then nearing 60psi or slightly over for the other two speeds. I do have oil in there and it is "full", not running low or too full. Sorry I was so long winded, wanted to give as much background for the help I need.
Thanks,
Marc
Any check engine lights or codes?
What is the mileage How is the tune up?

Wife has it out driving right now, but I think the mileage is about 41k-42k. This is an assumption and you KNOW what that makes me. I bought it about a month ago and assume the dealership did a tune up on it. More info on the burb though, I put it into 3rd and haven't noticed it chattering. Did notice that the rpm my be lower than originally thought, around the 1000 range instead of the 1500 to 2000 as I originally thought.

You might check the transmission fluid and fuel filter to start with..
But you need to get it on a good engine capable scanner and check out transmission and engine operation.
If you have only had it 30 days swig by the place you bought it and see if they have any ideas.
You may have some warranty on it.
If any codes post back codes.

Sorry, I forgot to post that the codes have not been scanned. I don't have a scanner and have yet to take it to somewhere that does. I would rather not go back to the dealer I bought it from, would rather be dragged thru cactus by a turtle. There is no warranty left, it was an as is purchase and it is over the 3/36 yr/mile that comes with them. Can a GM dealer put it on a dyno like machine and let me tell them how to recreate the issue? Our Chevy dealership is notoriously hard to deal with. I will see about the fuel filter tomorrow and maybe take off the cover on top of the engine and see if there is any loose connections to the injectors or anything else. Also, since it seems to be able to be recreated with a certain pressure on the gas pedal, could it be the Throttle Position Sensor. Because if I gas it or let off the gas the noise goes away?

Sorry, I forgot to post that the codes have not been scanned. I don't have a scanner and have yet to take it to somewhere that does. I would rather not go back to the dealer I bought it from, would rather be dragged thru cactus by a turtle. There is no warranty left, it was an as is purchase and it is over the 3/36 yr/mile that comes with them. Can a GM dealer put it on a dyno like machine and let me tell them how to recreate the issue? Our Chevy dealership is notoriously hard to deal with. I will see about the fuel filter tomorrow and maybe take off the cover on top of the engine and see if there is any loose connections to the injectors or anything else. Also, since it seems to be able to be recreated with a certain pressure on the gas pedal, could it be the Throttle Position Sensor. Because if I gas it or let off the gas the noise goes away?

There is several things it could be.
Engine or transmission running or even drive line.
The engine has to be running good for the transmission to work good.
Engine or transmission running problems will usually show up on a good scanner.
A good mechanic with a good scanner and a road test should be able to pinpoint the problem.
Some Tips on finding a good repair shop.
Good luck and let us know how it goes.
MT
Check around Ask around
Word of mouth.
Family friends coworkers neighbors business people and delivery people.
Mailmen and parcel delivery people get around and notice a lot of stuff.
Even a good parts house knows what shops are good and not good.
Chamber of commerce and better business bureau and city hall.
If you find a good referral to a repair shop go look them over and talk to them.
Look for a clean looking busy place with nice people running it.
Ask a few questions and ask about their qualifications and training.
Not all places have trained tech/mechanics.
If they do not find a place that does.
Even all dealers do not have all trained techs/mechanics.

I have a 2005 Suburban LS with 116,300 miles on it and I am having the same issue I think. I read a post on here somewhere that told me to try lightly pressing the brake while the shudder/vibration was occurring and if it stopped it was probably the TCC apply valve or the TCC regulator valve in the valve body. Tried this and the shudder went away on my vehicle. Haven't priced the parts yet. Hope this helps.