First thing first.
Get yourself a multimeter with duty cycle reading capabilities (Sears, 30 bucks), and start reading the codes.
There are hundreds of posts on how to do this, the same thing with the EHA valve.
When cold, more fuel is injected thru the cold start valve. May be you are running very lean when warm.
Please do a search, and read.
You will find the solution to your problem in the archives.
If you till have questions, post them.
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car