Well meaning family members try to help

My brothers gf’s grandmother is selling me her 1990 buick century. I was told it had a few problems that needed fixed but a tune up should take care of the majority of the problems. Its main problem? You stop at a red light and the car dies. And it takes several tries to get it going again. At first it wouldn’t even start back up. So Spark plugs wires and filter are bought and installed. GREAT. Problem solved with the not starting back up after it dies. HOWEVER it still dies at lights. When you put it back in park it cranks right on up. But try to shift to drive… or even first… it shutters and dies again. After taking my brothers advice on everything that needs to be done with it and 300 dollars later, he takes it for a test drive and says its perfect. I got myself a GOOD car. Well, I get to take it for a spin next. …My dad and I sat at a light for 30 minutes trying to get it to… move. It acted like it WANTED to engage, but couldnt. I got my brother on the phone and he said it was the starter module getting to hot and changing the chemistry and swelling and it had to cool off. So I let it cool off with the hood open. well the next two tries after that produced the same results, but third time seemed to be the charm. It sounds like metal is dragging though. My dad thinks my brother is full of it and says its the clutch dragging and not engaging or is engaging but trying to in park… or something to that effect. (Its an automatic btw.) Someone else told me its a torque converter and another an o2 censor and of course it could ALSO be a throttle problem??? Yea, I realize I bought a junker. I just needed a cheap car to get back and forth to college and my kids back and forth to doctor appointments. Any ideas?

The problem might be with the Torque Converter Clutch solenoid.

The torque converter clutch engages once the vehicle reaches 40 MPH. This provides a 1 to 1 drive out of the transmission for better fuel economy. If the torque converter clutch fails to disengage when stopping it causes the engine to stall. It would be the same as stopping a vehicle with a manual transmission in forth gear without stepping on the clutch. The engine stalls. Then when the engine is restarted it runs fine until the transmission is put into drive. Since the torque converter clutch is still engaged, this causes the engine to stall because it would be like trying to start off with a manual transmission in 4th gear. The engine stalls.

If you wait long enough, the hydraulic pressure eventually bleeds off from the torque converter clutch and it releases. Now you can start the engine put it in gear and drive off.

This problem is usually caused from a sticking torque converter clutch solenoid. Over time this solenoid accumulates gum and varnish on it where when it gets hot it sticks, thereby failing to release the torque converter clutch.

You might try adding a half a can of SeaFoam TransTune to the transmission fluid. The solvents in the Seafoam will desolve the gum and varnish on the torque converter clutch solenoid freeing it up.

Tester

‘Grandmother’s car’ is often ill-maintained ( this from personal experience ) as she simply drives it till it breaks. She has not ever taken active participation in it’s maintainence. She has never read the owner’s manual. She doesn’t change the oil unless prodded by friends or family. She never looks at the tires.

The car I got for my son from my grandma was a money pit.

You need to get ALL the maintenance recommended in the manual done. Assume nothing.
Get all the fluids changed, including brake and power steering. Avoid flushes at quick lube shops.
Get the throttle body and idle air control valve cleaned.
Get a compressions test.
O2 sensors will not cause drivability problems.

It’s 20 years old. How many miles? You have already spent more than it is worth…89, 90, 91, engine technology was changing every six months…Good Luck…

what filter was replaced? Air or fuel? try getting a pressure test on the fuel system

Yes so often it is good to start at the basics, plugs air and fuel filter are all done?