A9L ECU install, now it stalls out again and again...

First of all I have a 93 LX 5.0 vert with a 306. TFS aluminum heads, Cobra upper/lower intake, Vortech S-Trim @ 15lbs and no smog stuff. I was having trouble with the fuel pump not priming so after the long list of checks I finally replaced the ECU from my stock C3W to an ebay A9L. After replacing the computer the fuel pump primed as it should and the car started right up. I drove it for about 25 minutes (it ran great) when all of a sudden it stalled while cruising at 55 mph. I key started it back up and coasted to a red light as it stalled again. I ran down the battery trying to start it as it cranked but would not start. I finally got a jump start after about 30 minutes on the side of the road. I started right up and got me .5 miles home. I turned it off in front of my house and then tried to start it again after 5 minutes. No go. The check engine light illuminates when it stalls.

I pulled the codes and here is what I have KOEO- 31, 85. KOEO Cont. 18,31,96. Now here is the weird part when I do the KOER test it said it read a 4 cyl engine and gave codes 94,44,31. Then I did the KOER test agin and it said it was a 6 cyl engine with the same codes 94,44,31.

Has anyone seen this? Could I have gotten a bad ECU? It has the A9L sticker on it and does not appear to have been tampered with. Any ideas? The only previous problem was the fule pump would not prime with the key on. The only other thing I replaced was the fuel pump relay and the ECU relay above the computer.

Ok I have searched other threads here but can not find much about the code 18 (IDM...) What is it? Where is it located? Can I test this part to be sure that this is what is going wrong? I'll take any info on this part and problem that anyone has. Thanks in advance.

I have not had a chance to check for spark yet , that's #1 for after work tomorrow!!