I have been chasing this problem with my truck for quite some time now.
My truck idles fine in park when the engine is first started. After driving it a couple of miles it idles fine in drive but if you shift it into park/neutral it will begin to surge. Put it back into drive and it idles fine again.
I have replaced all of my ingintion components except for the entire distributor. I cannot locate any vacuum leaks.
The one thing that I have done that seems to affect it is to adjust my fuel pressure down below 38 psi base. This takes care of the surging idle in park but it idles very rough and my BLM readings go up into the 140 range when driving the truck. If I raise the fuel pressure back up to around 40-42 psi my blm readings come back down close to 128 when driving but the idle surge in park also comes back.
Is there anyone who can help me understand this.
My truck idles fine in park when the engine is first started. After driving it a couple of miles it idles fine in drive but if you shift it into park/neutral it will begin to surge. Put it back into drive and it idles fine again.
I have replaced all of my ingintion components except for the entire distributor. I cannot locate any vacuum leaks.
The one thing that I have done that seems to affect it is to adjust my fuel pressure down below 38 psi base. This takes care of the surging idle in park but it idles very rough and my BLM readings go up into the 140 range when driving the truck. If I raise the fuel pressure back up to around 40-42 psi my blm readings come back down close to 128 when driving but the idle surge in park also comes back.
Is there anyone who can help me understand this.