hard starting, rough lumpy idle, running rich, backfiring..help

[RpSinner]

before the only problem i had is that if i didnt let the car warm up enough it would die.

now its having problems starting...like it takes a few cranks. and when its running the idle goes between 400 to 900 and its a bit lumpy. also between shifts or after revving it it will backfire and shoot a flame out.

i was thinking it might be either o2 sensor or timing or both....

you guys got any ideas?

[PROJECTRB240SX]

classic bad o2... sounds like its stuck in the lean position and the car is running rich. I'm having this same problem.

[rancid240]

also check the ECT, engine coolant temp sensor, look it up in search.

[Nautious1]

also check your throttle position sensor (TPS). Check your timing to adjust the running rich problem.