Henry's 70 Dart Swinger

new electronic ignition is running well. but car was idling for about 10 min after driving it and it started to try to die again. if I revved it, it would cure it. driving on the street seemed fine...but if I floored it and got to the top of 2nd gear it would start to cut out. I'm thinking it is vapor locking. fuel pump is brand new high flow 6.5 psi.

car used to have rubber gas line going to the carb and never had this issue. pump was also different non stock style as well. it now has new stocking looking pump with correct metal line going to metal fuel filter, then up to carb. so I'm thinking maybe its heat soaking and vapor locking....either that or the gas is crap. running 93 octane.

I ordered a new SS fuel line, new gas tank, new sending unit, new tank pad, new filler gasket to tank, new trunk filler seal, etc etc.

dropped the old tank today, which was not the correct tank. it has a vent in the top center which is wrong. it was plugged off.

the old tank looked okay other then some minute sediment in the bottom, but the one thing I noticed is the sending unit did not have a sock on it. maybe I've been sucking up trash and that is what is killing the power. idk.

I would like to order a new filler neck as well, but I can't figure out which one is correct for a 70 swinger 340 with vent-less tank.

this one, which is on the car now

http://www.ebay.com/itm/171426119150?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

or this one without the vent.

http://www.ebay.com/itm/360938668372?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

seems like the vented one is for early a bodies and not 70, but I'm not sure....since someone put the wrong tank on the car, maybe they changed the filler neck...idk.

thoughts?