I have a 1989 civic sedan with a D15B that has had a multipoint intake from a ‘91 integra swapped in by the previous owner for max gains. Lately, it has been cold starting somewhat funny.

After it sits for a while and cools completely down, it will immediately light off, but stumble before going up to cold idle rpms, and rarely stall if I don’t keep cranking before it catches up. It’s only in the span of ~2 seconds, but it didn’t always do it. Then, if still cold, it may stumble when gradually rolling onto the accelerator while driving.

Cycling the key a few times to run the fuel pump didn’t seem to help, so I don’t think it’s a fuel pump or pressure but without actually testing it I can’t rule it out yet. Changed fuel filter just because it was due, and it didn’t change either. It may be a sticky IACV, which was an issue when I first bought the car. I’m going to play with it more when I get home and report more then. If you have any ideas!