RPM stumbling/engine dying ???

91 roadmaster 5.0. When I start it the RPM's king of stumble for a few seconds and then smooth out and idles fine. Go down the road and come to a stop and the RPM's again stumble and she dies? I cleaned the ground at the thermostat as told by Fred. Still having the same issue. Any help/input would be great.
Thanks
MildBill

My first guess is to look at the fuel pump. The hose from the pump to the output line may be cracked. Another possibility is the pressure regulator in the TBI. It might even be a partially clogged cat. Tihese cars are getting old, and the long term replacement items are starting to show up. How many miles are on it?

Idle control motor and air passage in throttle body.

Bill

There are a couple of other things to look at too. PCV passage in the TBI, and check for operation of the PCV valve itself. Vacuum leaks anywhere...the hoses are getting brittle.

Having the same issues. I recently had to replace the motor. Replacement was a used engine out of a 91 caprice, but I swapped all original bits over including the tbi I just cleaned and rebuilt. I find that a quick jab on the throttle will cause a surge or sometimes while at a stop light it will pulse like the car wants to move. Usually happens just before the car fully warms up. Is it the IAC or the tranny?

Check the hose in the gas tank for cracking. Check for any cracked vacuum lines.

It does not indicate anything is wrong with the trans.

I have cleaned and rebuilt the throttle body. New screens, gaskets, O rings and press reg. Found some carbon crud in the PVC port , cleaned all that out. Replaced the PVC valve and hose. Found a broken vac line going to the MAF sensor. Fixed that, still having the same problem.
Im thinking the next step is dropping the tank, replacing the pump and sending unit and hoses. I hope to do that in the next few weeks. I did however order a set of Mastercraft 255/60/15 tires, if all works out I will have matching wheels and new shoes on my boat first of the week.

Question about the cat. 186k on the car. Should I get rid of it and the 02 sensor. Or have a new cat and sensor installed?

Check the sensor before replacing it. If you do not have inspections, you can delete the cat.