Would a downshift modulator be the cause of sticking in lower gear?

What is your question?

the car does have huge mileage. It seems like s getting stuck in gear, especially in lower gear. Sometimes pulling out or going up hills I have to put it down in second to get it going. Usually once it gets to a high gear and higher speed it does fine. The problem mainly occurs in the lower gears. Someone told me it could be the downshift modulator so I'm trying to see if that's is likely correct or if it could be something else. And if anyone else has had a similar problem how was it resolved. Thanks