Car was jerked freqently during constant speed

I have one 1998 Chevy Prizm , automatic transmission, only 77,000 miles.

A month ago, I had someone changed the front brake pads for me. Since then, the car experienced weird problems.

Symptom: ============================================= When driving at about 35-40 miles or about 50 miles in constant speed, (in other speeds, it happened relatively fewer)

I could feel sometimes the car was jerked by something backwards in a very short moment, then pushed forward immediately for a very shotment.

Or it can be described as someone suddenly applied brake then immediately accelerate the car.

Someone explained this is because "transmission slip", the gear switched to a lower gear for a short moment and jumped back to the higher gear. That's why the driver felt something dragged car and then pushed the car.

The other mechanic explained as engine (or one of cylinder ?) died for a short moment due to spark plug or spark plug wire.

So for, I changed spark plug and transmission fluid (and gasket) but the symptom still there.

Before I would spend more time and money on the car, I would like to know what may cause the problem, what is more accurate or professional word to describe the problem and symptom.

=============== Transmission slip Engine stall Engine stumble ===============

Regards,

-Jeffrey

I think that's about the speed where the 'torque converter clutch' (TCC) is supposed to lock up the converter. If it was erratic, it seems like it could cause these symptoms. I think every Chevy my (extended) family has owned has eventually seen this go bad. It's been a while though, so I don't exactly remember how it acted.

Anyway, we would just pull whatever connector drove the clutch, and run without it.

George wrote in news: snipped-for-privacy@4ax.com:

which acording to GM should have fried the trany in short order due to overheating. KB

Huh. I'm surprised; it never happened to us. And, it certainly can run w/o the TCC forever, as long as you're below the cut-in speed. Do you have a source?

thanks for discussion,

So, what should I do now ? I' m not a auto geek...

George wrote:

If it was mine, I'd have to do more testing. And, I'd probably start by driving it with the TCC disabled. I'd start there partly because I'd rather it was that than some other transmission problem.

But, if someone I didn't know told me to do something I didn't understand, and someone else said "OMG, you'll burn up the transmission," the first thing I'd do would be to get a 3rd opinion from someone I trusted.

Of course, I would ask around.

Thanks again