79 Pace car not running well

[Sam]

My car sometimes idles rough and stalls. It has a low speed miss. The heat gauge runs very low all the time. any ideas?

[Thierry]

I had this problem on a car once and got the problem fixed with a new coolant sensor. I have been told that the sensor was sending wrong informations to the processor resulting in a lean mixture.
 Is the car acting up when you first start it or only when it's warm?
You could also check for vacuum leaks especially on the hoses.
There is probably many more reasons why it's not idling right but you can start with that until someone comes with more ideas.

[Sam]

I have a Chilton repair manual for 79 to 85 Mustangs and the information is mixed . Where is the sensor you are talking about on a 79 model? The book mentions a sensor on the right door pillar but that is not the location on a 79. Thanks!

[Thierry]

No the sensor is somewhere in the engine compartment. I don't know where it would be in a 79 Mustang or my own car but as it checks the temperature of the coolant, it's either on the radiator or on the intake manifold. It's also called coolant or water temperature sending unit. Your repair manual should tell you where to find it better than me

[Sam]

I have replaced the temperature sending unit recently but it didn't help. I resd in another book that the passageways under the carburetor can get clogged. These are the ones for the emissions circulation. I have been wondering if maybe this could be causing the problem. Any thoughts on this? The engine has over 100,000 miles.

[Sam]

  :I just wanted to update what I did to the car to try to remedy the problem. I installed new plugs and a new fuel filter, Cleaned out the emissions hose on the right valve cover and installed a new filter in the back of the air cleaner, installed new air filter, new pcv valve and hose, and checked the choke to make sure its opening properly. It still runs bad after it warms up and wants to stall and has a low speed miss. Any ideas would be appreciated.

[Thierry]

 What about the ground connection? A bad ground between the engine and the negative of the battery would result in the problems you have. Good luck.

[my83horse]

could very well be the egr,  after a while they get clogged