Help. smooth idle in P/N,but rough in gear

[80maroonbu]

my 80 bu has a completely stock v6 3.8L 231. it starts perfect and idles nice. but once i put it in gear, R or D, it idles really rough. i have changed ALL the vacuum hoses today except the one to the canister and tightened all the bolts on the carb. still no change. anyone have any ideas, or seen this type of situation? any ideas would be great.
thanks in advance
David

 

[Randy_W]

Check the distributor advance, if the timing isn't advancing under high vacuum conditions you may have a vacuum line in the wrong place, a stuck vacuum advance, etc...

 

[tc1959]

Check if your brake booster is leaking internally.

 

[80maroonbu]

i will check those things out guys. thanks

 

[VonbraunZ]

i curious as to if you found out what the problem is as my Monte Carlo with the Buick 231 has started doing the same thing you describe though when i put the car into drive or reverse it tends to just stall and die, and the only way to keep it running when i come to a stop is to keep my foot on the gas. now after about 10min of driving the problem goes away completely, any help would be appreciated and sorry for resurrecting a dead thread

 

[Clone TIE Pilot]

i curious as to if you found out what the problem is as my Monte Carlo with the Buick 231 has started doing the same thing you describe though when i put the car into drive or reverse it tends to just stall and die, and the only way to keep it running when i come to a stop is to keep my foot on the gas. now after about 10min of driving the problem goes away completely, any help would be appreciated and sorry for resurrecting a dead thread

Sounds like you may have a bad choke pulloff.

 

[Billys88SS]

I have also seen the modulator valve on the transmission cause this.