235 fuel system problems

[Rightrudder]

I’m new to the 235 model , this is the second time this has happened to me during a flight , first time i thought carb ice ,, this time i verified low fuel pressure when I’m running off the left main.

Flew for about 1 hr today . My left main tank when topped off will leak out of the overflow vent . Plus there is some of the blue 100LL fuel residue under the wing at the back edge of the tank . Today my left main was topped off when i cranked the heat up in the hanger to preheat the plane 45 degrees to 70 degrees ,it started leaking out of the vent tube under the tank . It’s happed before when the tank is full. So i preflighted did run up and off i went on the left main , about 45 minutes into the flight rough engine , carb heat on seemed to help looked at fuel pressure it was down to 2 , carb heat off then , i switched on fuel pump , it would go to about 3 , i switched to right main with fuel pump on it goes up to above normal.. I switch back to left main after about 10 minutes same issue pressure drops and engine runs rough .. on the ground on left main it seems to run fine , puzzling ..
Any suggestions please advise
Thanks

 

[sanjiv]

 

[Domenick]

 

[msires]

 

[skitheo]

 

[Rightrudder]

 

[gjvilla]

 

[Rightrudder]

 

[skitheo]

 

[gjvilla]