Trans wont shift into overdrive and jerky if you step on gas a little hard just started all of a sudden no problems before

When the Torque Converter Clutch (TCC) isn't engaging or locks in engagement the light flashes a warning...The TCC solenoid may stick due to dirty transmission fluid...If the Check Engine Light
(CEL) is not lit have your transmission fluid changed...If it is lit the code is probably pointing at a defective TCC, Computer (PCM) or the clutch itself... you can take the vehicle to an auto parts store and have them read and define the trouble code for free...saailer

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Check the fluid level. You may want to consider having the transmission flushed. (I recommend BG Products flush system.) Properly flushing the trans removes any varnish the may have built up causing erratic behavior.

Sounds like your trans is on the down side of burning up if it's an automatic. I'd have it towed to the shop. Could be as simple as a shifter solenoid, or a clogged valve body to as bad as having a trans rebuild.

too heavy a motor oil can cause hard shifting also,but when its cold out let your car warm up longer before you take off,it might help

If it had lots of miles on the trans fluid befor you changed it that fluids additives broke down long ago and wore out most of the fiber material in your trans,,its a problem with alot of gm makes ,unfortunatly you now need to rebuild at least a portion of the trans

when you step on the gas to the floor the trans is not trying to shift into overdrive, over drive connects as you are at a steady speed which lowers rpm and increase fuel mpg. when you step on the gas hard you are telling the trans to down shift to a passing gear,which calls for more fuel and air which is what you are not getting. A few things could cause this, bad crank sensor,ecm, fuel pump, fuel filter,knock sensor etc. I would get a full blown diagnostic done which will check fuel press,timing,sensors,codes,etc normally around $100.00 . But have this done at a very reputable shop and be there when they do it so they can explain everything to you, and make sure you understand things before somebody starts saying well it could be this and now i think its this or that.

I think rebuild try and service it if you find any lining material in the pan bad news

A common problem with most overdrive units.Overdrive should only be used above 40 mph. With the mileage odds are that you need to have transmission looked at professionally.It maybe time to consider rebuilding it.I do not see a trans service of being a benefit.

adjust your tps

Hi Joe, what you need to do is go to a trans. shop and have them adjust the TV (Throttle Valve) cable. You can do this yourself but you need a really low PSI guage. When the line pressure is at 0 - 5 PSI, it will be adjusted properly. Usually only trans. shops will have the proper tools to do this. It's very important that the TV cable is adjusted right on the money or you'll smoke your transmission.