Starts immediately, but runs ragged, as if it is flooded or missing. Opening the throttle slightly evens idle out. tach shows variable 600rpm to 900rpm, this occurs at cold start and operating temp start. Intermittently. Have replaced vac.hoses, cleaned throttle body,new air filt. At idle in stop&go traffic, will sometimes idle poorly at stop. Runs well at freeway speeds. the frustration is in the lack of consistency of complaint. obd shows no faults, fuel or ignition systems. checked f.i. vac modulator for fuel odor at hose, very faint. System has 188k miles. Replaced f.i. temp sensor when similar start difficulties occured 6 mos. ago, with obd fault code, problem cured with replacement. any help is appreciated in advance. thanks fred.