Running Rich or electrical problem?

[Omen]

Seems like a lot of mixture questions today so I might as well throw mine out there too.

 

 

77' 280z. Sometimes she turns right over some times I have to pump the gas few times and hold a little open throttle till I hear the belt slip the revs level out. I figured it was just the alternator and belt going but the voltage output is solid.

 

Then I started to notice the sulfuric egg smell when I opened her up and started to think it was deposits in the cat so maybe I'm running rich or maybe I'm not getting a solid spark?

 

Cat, plugs(but not distributor), and fuel filter are less then a year. Compression checks good and plugs don't look fouled last time I checked.

 

I do have problem with my deceleration valve not letting the revs come down until I'm at a full stop.

 

Bunch of symptoms are starting to look like they are all pointing to the same root problem. I'm just sure what it is. Any advice?

[NewZed]

 I have to pump the gas few times and hold a little open throttle till I hear the belt slip the revs level out.

 

notice the sulfuric egg smell when I opened her up

 

problem with my deceleration valve not letting the revs come down until I'm at a full stop.

 

Sounds like you're saying that your engine doesn't smooth out after starting as quickly as it used to.  Sometime there's a smell.  And your idle speed hangs high.  I'm not really seeing a connection, or much of a problem.  When did it last have a tune-up?  The sulfur smell is a product of the gasoline quality, I believe.  And the hanging idle could be a gummed up throttle blade.  Gunk from the PCV system can coat the intake all the way back to the throttle body.

 

A good tune-up and cleaning of the throttle body might get you back to normal.

[Omen]

6 months maybe. I'll have to check my Papwork if they checked the throttle body.

I know they checked compression, fuel air mix and And replaced the hoseing bits in the fuel rail and the fuel return check valve.