Ok....my 99 s-70 surges at idle and at speed. Between 1800 and 2300 rpm. The car shakes violently...if i floor the gas its fine..Ive replaced the MAF, Throttle body..What could this possibly be? it feels like a air fuel problem...any help would be great thanks

 

Fuel pressure good?

 

havent checked it..I blew out the fuel filter..What should it be at? and certin procedure to check it or just hook up the the schrader valve?

 

Hook up at the schrader valve with a fuel pressure guage.
You should be at like 50-55 PSI or so.

 

Thank's TECH will update tommorow.

 

Sounds good.