1993 Capri engine trouble
 

My daughter has a 1993 Capri (Not a zx-2). She has reported that while driving down the highway the engine appears to loose power and is very slow to accelerate. I, on a whim, opened the gas cap and was greeted with quite a bit of vaccuum from the tank (hissing noise as pressure was released from the cap). After this, the vehicle ran well and she was able to get home without any further issue. I need a little assistance in diagnosing this issue.

What I have thought of thus far; 1) the fuel cap is not venting properly (will be replacing it this afternoon); 2) the vent hose of the fuel tank is blocked, clogged, or damaged; 3) the rollover vent valve is stuck.

I could use any help that I can get as parts for this vehicle are hard to obtain and quite expensive when they can be found.


Thanks in advance.