I just installed a Mopar electronic ignition in my car. I used a chrome box. Anyway the car would not run without flooring it and would run on two or three cylinders, barely, at 500 rpm. I borrowed another dizzy from a buddy and it ran.

So I have a problem in the distributor. Obviously its in the reluctor. It is gapped correctly. Is my reluctor just no good? Where can I buy another one?

The reluctor wheel itself, rarely causes problems, unless it has been installed improperly.(it is indexed differently depending on roatation)
You can double check it by looking at the direction arrow on the reluctor itself. If the roll pin(between the reluctor and the dist shaft) is in the same slot as the arrow, the dist rotation should match the rotation of the arrow. If it's in the other slot, then it should turn the other way. This way they used the same reluctor wheel on BB and SB applications, even though they turned opposite directions.

The magnetic pickup itself can cause problems, but usually won't run at all. If you want to replace it, The pickup assembly can be purcahsed from a local parts store, and is fairly inexpensive.

Alright Dave thanks for the suggestions. The magnetic pickup isnt different for a performance application or anything is it?

Make darn certain that the springs on the underside of reluctor plate are still there and in the correct places; I have a MP dist. with some similar issues (regapped, replaced reluctor, etc), only to find one of the two springs had come off (if it was ever installed to begin with!) and was jammed in the dist body.
I'm currently using a crusty 73 dist, but at least this one has an operational vac advance!

drill a 1/2" hole in the top flat of the cap about 2/3 of the way between the center terminal and the #1 terminal and freeze the rotor w you're light & check rotor phasing. Use a junk cap if need be. I'm assuming the plates and the pickup assy are not loose. What gap are you using? since this is a problem case, check all 8 vanes w the brass gauge & I like .006 on the tightest one keeping mind that the vac can changes phasing and gap and w a Mityvac I find the tightest place on the tightest vane and set that one @ .006. Also check the ohms of the pickup & lastly if still no go might cut the 2 pickup wires and switch polarity then retime it as you're gonna replace it anyhow. Holler back w any news.