engine stalling and cutting out. Need Help

I have an 89 YJ with a 4 cyl. I have newly rebuilt engine with 500
miles on it. I have a new egr valve, alternator, and fuel injector.

When I engage first gear, the engine stalls and dies. Unless I sort of
prime the motor by letting off of the clutch and giving it gas a
couple of times. After I am driving the engine stalls and sounds
flooded when I go below 1900 rpm's or so. As long as keep the rpm's up
there is no issue.

The engine idles at @ 1000 rpms and doesn't have any problems until
the clutch is let out.

Any ideas would be greatly appreciated.

Thanks, 
Rob