reman. fuel injectors

I have an idle issue that has been happening ever since I got the car.

I have done:
-HG's (had a seeping HG)
-replaced practically all seals motor, tranny, diff., oil pan (Just a whole bunch of them..lol)
-replaced spark plugs

My idle has danced since I got the vehicle and after replacing nearly everything that has to do with idle it still present. It goes to normal idle most of the time but usually dances from about 900 rpm to normal. I replaced my fuel injectors with reman. from bostech on Saturday. The idle issue still there, but now I CEL (MIL) code 45 left metering which can mean several things. But since I replaced the FI I am thinking something is wrong here.
When I replaced the FI I noticed that there is a hard "fuel injector insulator" that goes into the motor and then there is a rubber "seal ring" that goes on the FI that sits atop the insulator. Now, the reman. FI came with rubber seal rings already that cannot fit atop the insulator because the rubber seal is too wide so I removed them and just stuck the injector with the rubber seal ring it came with. My mechanic insisted that the insulator is needed so he made me look for narrower rubber seal rings that will actually sit flush atop the insulator but I only found 2. So he installed all 6 FI's and used the 2 seal rings I found at the local store (they only had 2 left). So on the pass. side the 3 FI's were installed with the rubber seal ring it came with and removed the insulator. On the driver's side he used 2 of the seals I found and placed them over the insulators already on the vehicle. the other one he justy used the rubber seal it came with.

Do you really need to keep the insulator or can I just used the rubber seal ring the FI came with. Anywho, I cleared the code (took out underdash 7.5 fuse) and will take it to my mechanic today after work. I will check the code once again. Any thoughts will be appreciated. Thanks.