After looking on the internet, a number of entries were found about cleaning the throttle plate. The description of what to do seemed pretty straight forward so it was done. What you need is:
- an adjustable wrench
- old toothbrush
- clean rags
- can of carburetor cleaner
Next, take the adjustable wrench and loosen the O-ring from around the large air hose. Once it is loose enough, work the hose away from the pipe it is attached to. Move the hose to the side so clear access is provided to the throttle body plate.
Here is a picture of dirty plate. It is hard to get the camera angled for a good picture. There was a lot of black carbon build up in the pipe past the plate. The carburetor cleaner I used had a plastic tube that attached to the spray nozzle allow concentrated spray on to the plate. Once it was sprayed, quite a bit of black liquid came off which was wiped up with the rags. The tooth brush was then used to brush the inside of the pipe and throttle plate. Use your hand to turn the wheel that holds the cable that move the throttle plate to gain access to the back of the plate.
Once the brushing is done, spray more cleaner on plate and wipe away the carbon and liquid. Keep cleaning until black liquid quits appearing after spraying. Keep wiping the liquid up till dry.
Here is a picture after the cleaning.
Once all the hoses were put back in place, the engine was started and run for several minutes to get the cleaner through the exhaust system. One issue I had was the accelerator cable came off the wheel and when I started the engine the RPM went up to over 3000. After stopping the engine and placing the cable back its proper position, the RPM was around 1000-1500 at idle.
This fixed the problem and it made the car much nicer to drive.