Help! My 87 R3500 won't pass the idle CO part of the smog test. It's a 454 with TBI. At idel HC is 48 and CO is 1.86 at 2500 HC is 28 and CO is .88 I get 2 intermittent code errors: #32 EGR #13 Oxy sensor What I've done: Replaced EGR valve, solonoid and hoses New180 degree thermostat TBI rebuild, all sensor checked or replaced on TBI rebuilt distributor air filter spark plugs cap and rotor checked timing fuel filter oil and filter oxygen sensor checked PCV valve Took it back to the smog man, CO was even higher 2.81. Any ideas? Thanks, Eric M.