and while you're at it: also check the (short) hose that goes from you intake manifold to your idle control valve. it's at the back of the engine, on the passenger's side. it's a pita to check and replace, but often ignored/neglected. it took me 1.5 hrs just to get rid of the last piece of the hose at the intake manifold. if necessary, replace it with a piece (about 15cm/6in) of fuel line, inner diameter 8mm.