I was gonna post a real long post but erased it.

What would make my car die when i put it in gear d or r?

Has new alt,voltage reg, ballast, ecm.

When its running and i put a volt meter on the battery the voltage jumps all over the place from 13.5 to 15 rapidly jumping around.

I swaped out the battery from my daily driver same results.

Voltage bouncing around.

I dont know if i have a electric problem , fuel , vacuum leak,trans?

Car has 440 727 trans.

Starter has been going out for awhile. sometimes have to tap it with a long screwdriver to get it to turn over. Starts, idles fine. Put it in gear and it wants to die.

Having it running for awhile then shut it off. Cranks over very slow like battery is dead. Heat soak?

Switched out voltage reg and same problem.

sorry for the rambling just really frustrated !! Can someone point me in the right direction? As always thanks!

ported or manifold? what idle speed? what initial? recent problem? what carb? I'd take out the two idle mixture screws and shoot a 3 second blast of starting fluid into each port then replace the screws. slightly ream out the plastic nozzle on a can of starting fluid so you can affix one of those thin red straws to it to get the straw into the carb idle mixture ports for a good blast. On the slo cranking you always wanna start with the battery & subbing in a borrowed one will ans that real quick. might be dirty cables/terminals or ground path also or heat soak in the starter. far less likely is eng drag & I'm assuming not from too small of cables in a trunk batt app. holler back EDIT if you have 13.5 it ain't being undercharged. To pursue that further you might need a better meter or scare up an analog meter to borrow

Advance the timing, a 440 needs lots of advance
and the starter needs to be rebuilt or replaced

Besides making sure you have enough advance on your initial timing, I would look for a vacuum leak

A suspicious area is the power brake vacuum line, rubber grommet into your booster, and the plastic vacuum hose connector between the two first items.. Seen this afew times..

Update. Carb is a holley 3310 3. Timing is slightly advanced. Idle is set at 1100rpm.. A little high to help with charging. As rapidrobert said i removed both idle screws and cleaned with card cleaner. I did not notice a difference. I also used carb cleaner to check for vacuum leaks. Around vac booster ,carb, and manifold. Saw no increase in rpm`s. Dropped it into d and r. Rpms went down but car did not die. I feel i`m missing something.?? whats my next move?

try turning the idle mixture screws out and see if that helps with running in gear.

It ain't dieing now? More info please

Was the car previously running ok and this is a new problem or did you just put it together? If you just put it together, what cam do you have and torque converter do you have? If the cam is really lopey, you probably need a looser converter.

""Timing is slightly advanced""

What is your timing?