As the title says the in-laws 03 1500 with the 5.7 jumps around when idling.
Get it above an idle and it is rock solid.

Have done the ground wire trick for the throttle body and it did help for a bit.
Also had to put the nonfouler on the first o2 sensor.
Has new plugs even though the old ones looked really good.

The original motor lost compression on multiple cylinders.

Anything else to look for?

Thanks

 

Changed plugs and wires? Cleaned throttle body? Reset PCM?

 

Yes to all the above.
Will check for codes again and also the fuel pressure.

Thanks.