Help with rough idle under load on a 62 code 51 (searched and used FSM)

[Bomar]

When in D I get a rough idle. It is throwing code 51.

When driving she runs great and smoothly.

Then you stop at a light it seems the idle goes below 750 to about 600 or so.

I have ran about 2/3 of a bottle of sea foam and it seemed to work for a couple of days.

The ICS is working per FSM.

I have not cleaned the throttle body yet because the hose doesn't want to come off easily.

I am perplexed b/c it doesn't happen all the time but enough to bother me.

Looking at the O2 sensors they seem to have been in there for a long time so that is going to be my next project but what to see if this has happened to others.

In my search alot of people have a starting issue along with this but I don't so I have searched.

 

[cruiser88]

Start with cleaning the TPS but make sure you have a fsm and volt meter on hand.
if cleaning does not help check the spring inside....they like to wear

 

[cruiser88]

And pull the EGR to see how dirty it is along with the intake

 

[ad20k]

Hey Bomar, I had a fast idle / code 51 problem that was resolved by replacing the TPS and removing and cleaning the throttle body. I'm not sure which fixed the problem but its all good now. A used TPS is about $30 from cruiserparts.net. The throttle body has to be off to set the TPS per FSM, so that hose may need some coaxin'

Good luck.