84 K5 w/Quadrajet - Low idle in gear?

[Can Can]

I have an odd thing happening with the K5. The truck starts, runs, and drives like a champ. The only issue I'm having right now is that my idle is too low in gear while stopped at a light. Out of gear, the idle is fine.

If I take her out of gear while stopped, it bumps up to where it should be. The second I put her back into gear, it drops too low again. When I go to accelerate when the light turns green, there is no bogging or hesitation....

My choke is adjusted properly. The timing was bang on last I checked. I'm not running rich or lean, either. And as far as I can tell, I have no vacuum leaks anywhere. Of course, a vacuum leak should cause idling issues in park, too.

Does anyone have any ideas?

 

[Confedneck79K30]

vac. modulator on the trans? you could always try bumping the idle speed at the carb like 1/8 of a turn...

 

[southernspeed]

Does it feel like it's trying to 'drive' more than it used to when you're stationary in gear?
If the engines not bogging at all and running on all 8 at idle(?) it would seem to be excessive parasitic drag. 'tis a strange one though!

 

[Can Can]

vac. modulator on the trans?

I've got a 700r4, brother.

 

[Corey 78K5]

How many miles on the engine? Sounds like a timing issue to me and or worn cam. Also when was the last time You adjusted You valve train?

 

[Can Can]

The motor has 180K miles on it.

Like I said, Corey, the timing was bang on last ime I checked it. I *imagine* that the cam could be worn a wee bit, but you'd think that would also affect overall driveability. As far as adjusting the valves, it's never been done.

Does anyone else have any input? It just seem odd to me that the idle issue is only apparent while in gear......

 

[Corey 78K5]

I just thought of another problem You should check. I had fuel problems with Mine about 10 years ago. Ended up being rotted fuel line's on top of the fuel tank. They were the original factory lines and in bad shape.

 

[ryoken]

Run a couple cans of Seafoam thru that sucka... Throw em in the tank... Check for vacuum leaks as noted too...