I replaced the glow plugs this week on my 99 turbodiesel with BERU plugs. I had two that were bad with the glow light on. Removal was relatively easy with no broken plugs! The glow light/plugs are now working perfectly, but I have a slightly rough idle on cold starts for about 5 seconds. Then, the engine idles like a V8! I have no codes. I tested all of the plugs after installation;they are fine. Any idea what could cause this skip/roughness for a few seconds (even with new plugs)?

Thanks!