When I did the water pump on my car I broke this plastic vacuum line when removing the thermostat housing. I noticed it and fixed it with a short section of vacuum hose. This line supplies vacuum to the warm up regulator for the purpose of acceleration enrichment, so not only will there be a vacuum leak the acceleration enrichment won't work properly either. This is one possibility. What else was disconnected when you did the thermostat?

 

Thanks for the reply. I removed the tube you marked and what I think is called the secondary cold start valve which is just to the right of the wur in the picture and all the connections to it. I cleaned it up while removed and I think it works because the rpm’s go up when I discsonnect the leads to it. I took off the distributor cap. I had to loosen the wur to get to the hose clamp on the thermostat cover. I think that is everything I took off and I tried to check all the connections in the area so I think the vacuum lines are connected. The engine hoist bracket just under your arrow had to come off and I notice it is a grounding point, could it be that it isn’t grounding after assembly and causing the problem? Thanks.

 

The device next to the WUR is the idle air control valve, the idle increasing when unplugged indicates that it is working. The symptoms indicate a significant vacuum leak. As Dugald mentioned, what does the econ gage show at idle in neutral? Is it pegged to the left (normal) or somewhere in the middle?

 

Will the engine rev up in P or N in the driveway? Can you get it to rev by feathering the throttle?
What is the economy gauge doing at idle? It should indicate if you have a significant vacuum leak.

It’s possible your problem is unrelated to your thermostat replacement. Coincidental faults are not uncommon on old cars. Your symptoms could be caused by fuel starvation or blocked cats.

 

thanks for your comment. The car won’t rev in p or n or d. Even if I very delicately push the throttle it tries to stall. I also lubricated the throttle linkage and wiped off the air control plate while the air cleaner was off. The plate had a great deal of grime on it. Any other ideas? Thanks.

 

Thanks for responding. I think the gage is in the middle. I have to look again to be sure. Sounds like maybe I disconnected something that is not easily visible. Thanks.

 

When idling the Econ gage is almost all the way to the left.

 

Another line of thought ….
Maybe your engine overheating problem wasn’t simply due to a faulty thermostat. A severely restricted exhaust can cause overheating AND the problems you are now experiencing.

 

Excellent outcome.
Kudos to @AlterShinken for clever deduction.
I was off in the weeds.