Transmission or torque converter

I am not knowledgeable on automatic transmissions. Manuals are much easier. I have a 98 avenger with an automatic transmission. Over the last few years it has had the need to warm up during the cold days because the tranny slips. The colder it is the longer it takes. What is starting to happen is when it car gets going and shifts it will take a few seconds to finally go into the next gear. It shudders a little as it does. Sometimes it wants to stay in first gear and not shift up at all and the only way to fix that is to turn the car off and that seems to help. Sometimes the car will sit there in drive and not go at all until I shift the lever up and down a few times. Could this be the transmission or torque converter? What can I do?

And sometimes when I take off there is a winding noise and then a big shudder.

I suggest you start by checking the level of the transmission fluid and confirm it is at the correct level. Being a bit under full or even a bit over full can cause symptoms such as you describe. The fluid should be checked with the transmission up to temperature, the vehicle on a level surface, and the engine idling with the transmission in Park. While you have the dipstick out (which I assume your '98 Avenger is old enough to have) visually confirm the transmission fluid is not dark like old engine oil and give it a sniff test. If it has a strong, unappealing odor, it's time to be replaced.

If the oil level is not correct, correct it before getting too excited about a major issue. If the fluid is dark or smelly, change the transmission fluid and filter. I would not recommend a transmission fluid flush as that could do more harm than good.

-Rod

I suggest you start by checking the level of the transmission fluid and confirm it is at the correct level. Being a bit under full or even a bit over full can cause symptoms such as you describe. The fluid should be checked with the transmission up to temperature, the vehicle on a level surface, and the engine idling with the transmission in Park. While you have the dipstick out (which I assume your '98 Avenger is old enough to have) visually confirm the transmission fluid is not dark like old engine oil and give it a sniff test. If it has a strong, unappealing odor, it's time to be replaced.

If the oil level is not correct, correct it before getting too excited about a major issue. If the fluid is dark or smelly, change the transmission fluid and filter. I would not recommend a transmission fluid flush as that could do more harm than good.

-Rod

The fluid is correct. It is dark like old engine oil and I didn't smell anything. Could old transmission fluid really cause the transmission to act up like this?

When transmission fluid gets burned up it thins out and loses its lubricating properties. It also loses its ability to maintain the proper level of hydraulic pressure that keeps the power output and gear changes smooth. Change your fluid and filter and post back about how that works out.

How do I find out how much fluid it holds?

That kind of info is usually found in the owners manual. If you don't have the owners manual, you can probably find it at a dealership, auto parts store, or as a pdf document online somewhere.