Hi fellow C4 people
first thank you to the help I got getting the car running (mr.ihbd especially)

I am now dealing with a rough idle/intermittent stutter. No codes showing up.

I bought the car running but wanted to clean it up some. It all began with me doing the lower intake gasket. during this I also installed new injectors (oem specs). I ended up putting it back together and then taking apart again to the water pump immediately.
I then had a fuel injector issue which turned out to be a faulty ignition module in the distributor. Then once it started it was running horrible.

I thought I had a code for a bad IAT sensor, but that was a CCM code not a ECM code. It got replaced before I realized.
I checked fuel pressure and it was about 30 running, so I decided to replace the fuel filter. It dropped to 20.
I replaced the fuel pump, and it was at 42 then seeped down to 38 or so as it ran. The car ran a little better.
I pulled all the plugs and checked for spark, they all had spark, but one smelt like gas. They looked old, so I replaced them.
The idle has greatly improved. It seems to run well, until it warms up and you give it some gas...then the random stuttering starts. It really seems completely random. backfires on decel alot too. (straight piped)
I sprayed around with brake cleaner to see if I could find a vac leak, and no dice.

I have an obd1 reader on the way, but not sure what to look for once I'm looking at the data. Theres no codes right now.
Oh, and when I start the car with the maf unplugged, it runs rough for a while then dies.

One thing I noticed is my oil temp reads 0 on the dash, but I figure its just a bad switch...would that do this?

 

Coolant Temp Sensor

 

ill throw my extra temp sensor on there!

 

I replaced the coolant temp sensor on the front of intake manifold and it runs worse

now the idle is very rough, whereas I had gotten to the point where there was just the stutter...but i assume this is indicative of larger issue

also I decided to see what would happen if I try and drive it... it lurches HARD until i get into higher rpm, then stalls when I push in the clutch, sometimes

 

was this extra sensor the original one or a known good one?

 

at idle the IAT solenoid is controlling airflow, you mentioned the sensor have you checked the solenoid?

sensors like MAF, coolant temp, IAT and O2s control fuel. If your scanner has live data you can check to see if they are in factory range

regardless of technology level, engines are still air, fuel and spark at right time and amount run fine

 

I took the brand new one out of the IAT spot and used that one. So it should be good.

I put the one that was originally in the IAT back in where it came from

 

I haven’t checked the solenoid, where is that?

scanner isn’t here yet. I haven’t received any shipping notification either. Does anyone know if red devil river is still in business?

 

 

Oh fyi PO has this blocked off with the throttle body bypass but it did run before fine like this.

 

I replaced the IAC valve and not much change. Today was cold, but something new, tons of white smoke from the tail pipes when I’m idling. It’s only on idle and like after coming to a stop.

I tried to drive the car today as well, and especially in first it surges forward at low rpm. Tons of small backfiring. It is straight piped so I know some is normal on decel but this is everywhere. And it died while I was exiting the freeway in neutral.

so far:
new intake mani gaskets
new injectors
new water pump
new IAC valve
new coolant temp sensor
new fuel pump
new fuel filter

still unsure of the status of my cable. Might have to chargeback order and get from another place… so a little blind on the computer sides of things. Any other tests I can do in the meantime?