I have a 240D manual that was converted to a 5cyl non turbo. The car starts and idles smooth for about 5 seconds, then starts to stumble just enough to make the car shake really bad. If I rev it up a little, it runs smooth. The GPs are new, and it has a new set of rebuilt injectors. The valves have been adjusted. Once it warms up a little, it is okay.

Any ideas? Thanks.