hello everyone, new guy here. what i have is my sisters 1999 cougar with 2.5 engine. (150.000 miles) it had a multitude of codes.po 171, 340,1131,1401.i managed to clear these by replacing the dpfe sensor,pcv valve, egr press. sensor. i also replaced the b1 ho2 sensor (scanner showed .1-0 volts) what i am getting now is a code po401. that comes and goes. i have checked all the vacuum hoses, cleaned out the egr passages. i will clear it and it comes back in about 1 day. i also cannot set the readiness monitor. i need this to pass emissions testing. i heard that there was a tsb on the egr system for this car, but i don't know if that applies. i would appreciate any help as i am sick of working on this heap. thanks again.