I think my ECM is new enough the failed resistors aren’t an issue. Mines an OBD II 96I am actually chasing a similar issue with a x90 at the moment with a 16v, won't idle for shit and I've gone through everything. No vaccum leaks, great compression, valves are in spec. Changed the idle air control valve with a known good one and same with the egr valve. I'm changing the ECM next, I have a suspicion that it has bad caps or something causing the ignition to malfunction at idle speeds.
So is this one, it's a 97. but I've had 2 failed obdii ECMs in my wheeling groups fleet of 7 zuks with 16v engines. (I built all of them and help them maintain them) I'll keep you updated if it ends up being the issue, if so I have a source of ECMs and I can ship one out to you to try.I think my ECM is new enough the failed resistors aren’t an issue. Mines an OBD II 96
I’ve already eliminated those two problems from the list of possibilities. You can pull the vacuum hose off on the engine side for the vac booster and cap it to see if that’s causing a misfire.Update, I found the fuel pressure regulator was bad. And so are my two parts ones 🤬
See if yours is pissing fuel into the intake, if not unhook it from vaccum and plug the intake port and see if it idles better. If it does start there. Cheapest I found them was on eBay for 10 bucks
Edit- I also found the master cylinder is leaking vaccum around the vaccum booster, might want to spray around there and see if that is leaking as well