Need help to fix my nissan

I have a 86 nissan with a 3.0 v6 in it. It idles fine and revs up fine untill you reach 2k rpm, once it hits 2k it goes right back down to 800 rpm and sometimes backfires. This is getting frustrating i cant seem to figure it out... anyone have any suggestions? It has a new fuel pump, filter, and spark plugs.

Sounds like fuel delivery problem. Check all the fuel lines make sure you flow is good.

Is it fuel injected? If so, did you check the MAF?

My 97 with 2.4 is doing the exact same thing. It doesn't always backfire but it'll bog down and then go back to normal. I've checked everything I can think of but still can't figure it out.

well if it backfires its uasually getting to much fuel for the ammount of air. becasue the gas is lighting off in the header. so i would look at your MAF. Just my $.02

Thanks for the information guys. im gonna do some more troubleshooting to the fuel system today.. Im going to hook up a inline pressure gauge and see what is going on there... Hopefully I will identify the problem,
I am thinking the pressure regulator might be bad but who knows.....

Any check engine light?
I had a TPS go out once and it was similar

Well I noticed the positive conection to the fuel pump at the sendng unit was horribly corroded and not making a good connection, so I fixed that.. I also replaced the fuel pump (it was still under warranty). Now the fucking thing wont run for more than 2 seconds then it dies.. Im about to set this fucker on fire!!!! The check engine light is not on but who knows it could still have a code. I have an ODB2 but no way to get a ODB1.... Anyone have anymore ideas?

maybe the fuel pressure regulator...check ur distributor....injectors...als oget a guage and check the fuel pressure im not sure what its supposed to be but the dealer or a chilton manual will tell u and that will tell u about the regulator...

my 94 does the same thing used a code reader it comes up with a throttle position sensor haven't changed it out yet to see if it fixes it yet