Installed new rubber hoses for idle air valve. Hoses were cracked and most likely were leaking vacuum. I also found that EGR valve membrane didn't hold vacuum as well. I disconected EGR solenoid to eliminate vacuum leak. Found no more vacuum leaks. I have exhaust pipes disconnected of manifold but It was insainly loud to drive around. Im thinking to get free flow cat and make shop weld it on to eliminate possible clogged cat problem since car has 180,000miles on it anyway. Adjusted my duty cycle to 45% on idle BUT when I rev engine to 2500 duty cycle goes to around 36 to 39%. As Ive seen on this forum average should be around 50%. When I average 50% at 2500rpm, Idle cycle goes to 60% to 65%. I read on this forum one member has his duty cycle 45% Idle,50% 2500rpm. Car feels much better with vacuum leaks eliminated but still has poor gas mileage around 14mpg city. Im not heavy on gas pedal so there must be another problem. Any ideas?
Thanks

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1999 ML430 Silver 135k ml
Smoked LED taillights, Alpine in-dash DVD player, 12" sub, Pioneer components, 2 amps, 4200k HIDs, ML55 headlights, 20" rims, mirror LED blinkers

SOLD. 1996 E320 145k ml. Burgundy

SOLD but miss it everyday 1992 500sel Black
Chime buzzer mod,Alpine CD/MP3 player with stock amp,Euro headlights,S600 grill,20" rims, BEST CAR EVER!

SOLD. 1990 300E White
187k ml,smoked tails,Euro headlights,17rims,Intake,12" sub in first aid kit,alarm/autostart,buzzer mod