Idle issue with replaced fuel pump

[JeLani]

Just replaced my fuel pump because the old one, ( which when i took it out looked like it had been to hell and back) had been causing accelaration problems while revving high. But now it takes longer for it to warm up, it has always idled weird starting. When it idles the revs will intermittently drop then suddenly rise. But today it drops to the point where it almost shuts off because the dash lights flash and when it rises suddenly they'll shut back off... Until it idles straight. Just now when it did that , it also followed a couple of louder idle rises then the usual ones that happen when it lowers then rises
Example : 430rpm--700rpm--430rpm
Just noticed now : 430rpm--700rpm--430rpm--900--rpm
Could it be my injectors now?

[JeLani]

also the startup is poor. my battery light is also red :/. but it hasn't been in the car, should i recharge? my voltage regulator and battery are both new.

[5Toes]

get the fuel injectors rebuilt, imagine the condition they must be in since they are the same age of the pump.

and then check for vacuum leaks.

[JeLani]

someone just told me i should replace my 02 sensor based on how i described my problems. The car has a replaced cat,not new im sure, the PO was a jackass. Could this be involved too?

[nando]

Unplug the O2 sensor first. If it runs the same, then your O2 sensor isn't causing the problem.

to be honest it sounds more like either a vacuum leak or perhaps the ICV getting stuck or otherwise not operating correctly. A stuck ICV could cause surging idle & poor startup.

While I'm sure your injectors could use service, I doubt that's the central issue here..