94 4.0 ranger won’t idle

[ryantodd1999]

If have 94 4.0 ranger 4x4 have to start 2-3 times to get to start rpm spike to 1500-2000rpm then dies once it does start idle surges between 500ish and 2000ish rpms when I press the pedal it surges between like 3000 and 2000 rpms
The whole fuel system from pump to injectors has been replaced fuel pressure stays beween 30-40psi, all intake gaskets have been replaced. Iac, tps are also new. When I unplug iac it try’s to low idle for a second then dies. I have checked all wiring no shorts, when I hook up scanners and do the koer test I get 411 and 412 codes. Seem to surge less when the ect and iat are unplugged but still not right. When I use scanner all sensor data looks good other then the o2 sensor show constant high and low readings in conjecture with each other unless I unplug iac then stays at rich .4v

Edit: for get to mention new coil wires and plugs and yes they are hooked up on drive side the right way

 

[SenorNoob]

Did you buy it that way? Any work done around when the problem started to show?

For other readers reference:

411	(R) Idle speed system not controlling idle properly (generally idle too high) – ISC
412	(R) Idle speed system not controlling idle properly (generally idle too low) – ISC

Sounds like the new IAC isn't good to me. Or you have some kind of intermittent vacuum leak.

 

[ryantodd1999]

Did you buy it that way? Any work done around when the problem started to show?

For other readers reference:

411	(R) Idle speed system not controlling idle properly (generally idle too high) – ISC
412	(R) Idle speed system not controlling idle properly (generally idle too low) – ISC

Sounds like the new IAC isn't good to me. Or you have some kind of intermittent vacuum leak.

It was given to me that way the guy that had it before me replaced all the parts just before I got trying to figure out the same problem. When I got it I figured it was the iac so I replaced it and it didn’t help

 

[ryantodd1999]

So I tried another iac and nothing changed

 

[SenorNoob]

Smoke test time?

 

[ryantodd1999]

Smoke test time?

I already did that nothing showed up out of normal