1985 Pontiac Firebird Car hard to start

I forgot to say it is a MFI not carburated. Sorry about that.

Thank you. Well the leak appears to be on the passanger side. If you look at the engine from the front you will see the fresh air intake hose going into the engine's plenum. There are two pipes that go into the plenum right next to the TPS. I can see a drop of something hanging from one of those two pipes right underneath the fresh air intake hose and a little puddle right underneath those pipes on top of the plenum right underneath where the hose and the fresh air flap assembly meet. I have not check the fuel pressure regulator how I do that. Another thing I noticed before this problem started was when I open the gas tank to put gas there was a lot of pressure out almost like the gas cap wanted to fly out of my hand and a lot of smell of gas. I replaced all vaccum hoses with the exception of the ones leaving the EGR and the vapor canister ( they still look in good shape )
The problem started last week with high RPMs on idle, then hard to start, then after it started when you give it gas started to splurr and car died. Now I can get it to start after few times but then engine shakes and on idle the RPM eventually jump to 1500, I put it in gear and shkes go away and then RPMs are in the 500-600 range. Turn the car off and it starts right away. I let it cool down for 10 mins and it is hard to start again.

I did buy a new gas cap and it was done last week before the problem started. When was the gas filter replaced? I bought the car maybe 3 months ago and I have not replaced it. Don't know when the previous owner did so.
I had this starting problem before but since I had aon old battery I never got it to start before the battery went dead. Usually car did not start, my mech towed the car and when they dropped the car it would start fine so he couldnt figure out the problem. He had me replace the alternator but problem continued every two weeks or so thats why i'm not taking my car to him ever again. Now problem is worse and everyday I'm just killing my brand new battery and starter trying to start the car

I think I got a non-vented cap but I will switch to the other kind and get the fuel filter replaced. Seems like you and my new mechanic share same thoughts on what it could be wrong with the car as he told me that it may be a problem with the coolant temp sensor. I will take the car to him tomorrow and will share the results.
Thank you so much for your help! Excellent service!

Well my mechanic said that he needs to replace the entire fuel regulator and he said that part cost like 220 bucks plus labor he said total of 500 bucks. Im kinda suprised because I looked up it on line and the most expensive one I found was 95 bucks.
Any suggestions?

Thank you for your help. Its just too much gas going and seems like its not going back to the tank. If it is a plugged return line or a bad fuel pressure regulator how I check for that?

Ok I replaced the fuel regulator and I think that corrected the gas issue. It started fine, no gas leak and real quick but today I went for lunch at work and it was just not starting until I tried for a few times and at the last time I just kept my hand in the switch and it started but maybe 10-15 secs later. I tried again and it started ok. I drove it for a few and park and try to start it again and it worked fine.
Someone told me it could be the distributor as once before ( yeah this happens once in a while before the gas issue ) I got no spark but then the car gets moved such as towing it and when they put it down it starts fine. Maybe new module and coil?

Thank you for the advise. I replaced the ignition module and it starts just fine now. I am replacing the coil as well just to be safe.