A quick update. After replacing the bits (breather pipe and plugs) and found it still not running right, I disconnected the battery and let the ECU reset. Once I started it up and let it idle (which it did) for about 10 minutes, it appears to be running fine. No stalling, idles about 750rpm though I've noticed something else!!

The speedo jumps occasionally and when it does, the radio gets louder for a second or two. Any thoughts? It's not a big issue - the main one was getting it to run without stalling! But I thought I'd ask.