mechanic needed

[moondog]

I have a 78 bronco ,351m c6 ******, I have been driving this truck since 1989, the truck will start and idle all day long, not even a hiccup, but when you pull it down into drive it will run until it shifts into second then it starts bogging down, when its starts doing this , if you put the ****** in nuetral it will rev up with not even a miss, put it back in drive and it starts the bogging again,I have rebuilt the carb, replaced the ignition module, dist cap,rotor button, coil,replced the mechanical fuel pump with an electric one, replace the vaccum advance, and the coil pickup in the distibutor, plugs and wires enven the ignition switch, this thing is driveing me up the wal , any suggestions?

 

[Camp David]

Torque converter?

 

[dh1984]

Torque converter?

Thats what is sounds like.

 

[Good time Charlie]

I would check the Modulator valve first..but like has been said it has to do with your torque converter.

 

[fredfred]

What's the timing set at?

 

[moondog]

When it starts this bogging or stuttering it seems more like an electrical problem, the ****** is shifting fine the truck will run but you have to stay abouve 45mph and seems worse when its in a pull such as going up a hill.

 

[ImThere]

Fuel pump

 

[SilverFox]

Hope you figure it out. My old Ford did the same thing. Chased it for a month or so before it ended up being a cracked spark plug... But if you've replaced yours already I wouldn't think it's your problem.