Popflyz13

With cooler temps coming, I gotta get on top of this. Advice welcomed!

When starting cold, the engine fires immediately but balks at starting. Once started it will idle but there is little power and significant stumbling but particularly when under load. The warmer the outside temperature, the easier it is to start. It starts and runs reasonably well when hot. Warm idle is high at 900+ rpm.

The following is new within the last 6 months:
Multi-function temp sensor
Spark plugs
Fuel distributor
Fuel accumulator
Fuel filter
Cold-start valve
Check valve
O2 sensor

The temp sender (guage) just died but hasn't impacted things one way or the other. New one ordered. The radiator fan seems to be cycling on-off as it should.

Fuel tank and FP intake was cleaned so there is no problem there. The fuel pump whines ocassionally and will get replaced soon but I doubt that it contributes to the cold-engine/stumbling problems. The exhaust is kinda stinky and mileage is down from before the dizzy replacement, so I'm sure the car is running rich although I 'm not sure why.

Its driving me crazy. Any ideas?

AudiSport4000

Coolant temp sensor

Whitjr

For the mileage loss.... Since you've done all that to the fuel delivery system, you will likely need to adjust the mix. use a "t" handle 3mm allen to insert into the small hole, and adjust [in small increments] one direction or another... this is the ghetto way of doing it, howevere it works nicely. the real way to do this adjustment is to put it on a machine that will give you precise measurements.

You don't mention having new wires on the spark plugs, or dist cap & rotor. BTW there are 2 fuel filters down there, did you r/r both?

Katman

Mike: You are starting to sound like me, going on about the coolant sensor...!

But Mike has a point:

What makes the mixture rich when cold, and leans it out when the motor warms up?

That's a good place to start looking.

AudiSport4000

I know if I end up getting a 10v 5cyl car that is one of the first sensors I will replace.

That could be the culprit in this case. The rough running immediately after startup was an indicator for me.

SpecialBuild87

Indeed my exact problem and cause