budlyte,
Replacing the injectors is no big deal 1.5hrs at most easy diy. The fuel distributor is painfully expensive avoid this at all costs.
0. Do this first get the car on a scope and make sure you have a nice firing pattern and have the lamda adjusted to spec. This will tell you if you are burning to much fuel or if the hydro carbons are not where they should be.
1. Check your plugs, wires and distributor.
2. Check all the vacuum lines
3. Check the rubber breathers to the injectors and idle control valve.
4. check your idle control valve
5. check the idle control relay.

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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)