i have a 95 dodge van b2500 5.9 check engine light is on, code 27 en then bad smell of gas from the exhaust also like a blue smoke from the exhaust chnage to many parts but same problem comes on change sparks plugs, wires, O2 sensor, tp sensor , map sensor, air control sensor, distributor cap and spiner, fuel pump,injectors,check all the wires for injectors, code 27 is the only one showing.I realy need help i don't what else to check please helpme.