1995 Nissan pickup running rough at idle, especially with air conditioner on

back fires is timing . Sounds like you didn't have the no one piston at DTC when you put in the new distributor if that what you meant by new rotor. If you meant new rotor button and distributor cap. Check the rotor button and cap are installed correctly.

Yea it was running rough before I replaced the rotor and distributor cap. Any other ideas? Thanks

the back fire makes me think check if the distributor is loose .It sounds like it has turned some from when it was once timed. The only other thing that relates to timing is cam sensor to ECM to Coils and plugs, Crank it up and unplug one coil at a time see if it gets worse. Sounds like it could be a failed coil that would cause a miss fire. No codes stored?

No codes

The backfire is rare and minor, but the missing when the air is on is more pronounced, once the truck gets going up to speed it stops missing Thanks

put in a fuel additive to clean the injectors

Yes I forgot to mention that I already added Lucas fuel treatment to my last tank of gas Any ideas? Thanks

check all the injector connection are secure and no moisture where the coils attach to the plugs

Thanks I’ll try that

also a clogged cat can cause this

How would I diagnose a clogged cat? Thanks

https://www.bing.com/videos/search?q=how+to+diagnois+a+clogged+cat&&view=detail&mid=7426DC9705BA3E22F81D7426DC9705BA3E22F81D&rvsmid=C70A30146505550838A3C70A30146505550838A3&FORM=VDQVAP

that's done with a pressure gauge in the o2 sensor hole

Thank you

FICD...AAC....CHECK THEM BOTH. FICD works in conjunction with your AAC. (IAC) when you turn on the AC, the FICD activates and lets more air in to run AC and keep idle normal.