Is this normal?

After searching these forums I think its not, but I am stumped.

The car is a 1991 buick regal with 120k. Recently, i tried starting the car when i forgot to put the oil filler cap back on and found out about this issue. The car runs very well, no stalling, idle problems or start up issues when cap is on. It has plenty of power.

The pcv is correctly positioned with an oring and gasket for this model year without an EGR.

There does not seem to be any vacuum leaks.

I replaced the LIM 10k miles ago ( last year) more of a preventive measure since it started to get some oil in the resevoir.

The thread "92 oldsmobile 88 stalling when cold fine when warmed up" dated back in 2006 was useful, but I am still stumped why it does this.

Any help would be appreciated.

Correct me if I'm wrong guys but this almost sounds.....normal

On Series I motors, if you remove the oil cap before or during the motor is running.... wouldn't this create a huge vacuum leak?

I've had the oil cap removed and started the car with no problems on multiple Series II motors.

But since there is no EGR on your motor than it probably is sensitive to not having the oil cap on when starting or running.

I'm leaning towards a huge vacuum leak situation also. Though I'm not familiar with the series 1 motors, I have heard of similiar situations when people have put on fancy breather caps as part of an engine dress up and then experienced poor engine performance.