Engine Code

[H8 2 W8]

Hello everyone. I've been around this forum for a long time, but this is my first post. I need help with a confusing engine code. I've got an 1981 Porsche 928 Euro 5sp. My VIN is WP0ZZZ92ZBS841366 which confirms that my car is an 81 Euro. However, my engine code is 28/22. When I looked up the code, it shows 28/22 as an 84 Euro auto. Do I have an 84 engine or just block? I'm confused because I believe my top end is 81 Euro. I don't know enough about the 928 to figure this out. I need to know what I am dealing with because I'm trying to troubleshoot a stumble on acceleration issue. My car was running fine and out of the blue it started stumble or flood when I accelerate in any gear. It idles fine and will drive ok in low rpm range, but if I give it gas, it will just bog down. I've replaced the fuel pump and filter, still doing the same thing. I have limited tools and knowlege, but I want to figure this out and not have to take it to someone. Any help/thoughts would be greatly appreciated.

[H8 2 W8]

Additional info. I checked the vacuum lines and they are all connected and appear to be in good shape. Car starts on the first crank every time. It just seems to be fuel related, but I'm no expert. Maybe fuel pressure regulator? WUR? Does the timing get out of wack that easily?

[stepson]

H8, Are you reading the VIN# on the fender or the door?

The fender VIN will always have ZZZ VIN#. The one in the door is the correct VIN#.

Apparently, someone has replaced the block in your car with a 4.7L 84 Euro block and moved the CIS and ignition stuff from your original engine to this engine.

[H8 2 W8]

Hey, thanks for the response. The #is from the fender. That helps a lot, now I know I need to replace the CIS parts as I troubleshoot. Thanks again.