Rough idling in Drive

[wmring]

I have a few questions, I just purchased my 1971 F100 with a 302. I had the engine rebuilt along with the Carb.

The truck starts and runs fine until I put it in drive then it wants to die unless I step on the throttle.

While driving it seems to shift hard or not at the right time by engine rpm (no tach but listen by ear).

When I come to a stop I generally have to keep my foot on the gas slightly or it will die.

Leaving the truck in drive an not stepping on the throttle the engine will die.

Truck idles fine in park

Thoughts on this?

[Mancar1]

You probably need to increase the RPM at idle. What do you have it set at idle now? You may have a shift kit in the tranny.

[wmring]

I did that today and it helped I don't have tach or photo

[tnlprt]

You might want to check the vacuum hose that goes down to the modulator valve on the trans

Also check the modulator valve itself

[wmring]

I will look into that, my mechanic shop guy didn't think it had one on the 1971. Any idea how I could verify if this year truck came with the modulator valve? Where is it located on the trans?

Via Faxon I have ordered all the shop manuals on CD for this truck that should show the location

[tnlprt]

crawl under the truck

look where the pan bolts to the case right above the crossmember and you should see the vacuum line going into the modulator valve