My kind of in the same predicament w/my 77 2.7. Not too many 911 stock 2.7 MidYears in my locale or anywhere it seems, so comparisons and advice is best here.
The thing about my vac leak was that when i found the hose was hissing, replacing the booster hose altered the idle or Mixture that was set by PO. It actually ran better w/broken hose! I can only guess how many cracks in other hoses that are hidden in engine bay. See pic.
You can try a garage tweak with the FD mixture screw, 1 or 2 clicks counter-clockwise to lean it out. Where’s your idle set, 950 ? Some say older engine will run better a bit on the rich side. Pic of my tailpipe, no soot so I’m not set at that overly rich mixture. I’m waiting now until I can get into the shop to do some proper diagnostics and assessment. Oil seep is white smoke that one would see from worn valve guide, it was like a smoke house when I started up after 4 month hibernation…I’m at 200k, with last top end prob at 100k.
Surely check those plugs and gap again. Think there was some debate about using Petronix on the 2.7. Yes, No points/no dwell.
Being in storage kind of lends itself to lack of driving. I’m no daily driver so I’ll go out for a 30 mi highway, 5 mi stop/go city street jaunt at week once a week, always coming back running better than when I cold started.
https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/31-CIS_Fuel_Injection/31-CIS_Fuel_Injection.htm
