Warm Start - Brief Bog Then Fine

[ascott430]

Hey All.

I've been trying to track down a pesky, but not too inconvenient problem with my 91 318i. Engine cold start up starts and runs just fine. A couple cranks, smooth idle and I'm on my way.

Warm engine start up. Cranks and starts just fine but then idle hunts around after about 10 seconds. When taking off from the driveway the motor bogs but you can power through the bogging. Power through for about 5 seconds and just like a switch the engine suddenly smooths out and delivers powers normally. Engine idles fine. Any thoughts?

Here are a couple things I've done...
In line fuel check valve
New 02 sensor - but didn't check condition of connector pins
ECU coolant temp sensor
Fuel pressure (pre rail) doesn't dip when engine is bogging
ICV cleaned
No vacuum leaks seem to be present
My next step is to look in to the fuel pressure regulator or possibly leaky injectors. Also, after replacing the sensors should I reset my ECU?

Thanks!
Alex