Have you checked the ecu/dme coolant sensor. If faulty it may be over fueling when warmed up, which could cause the above mentioned symptoms.
Some may know this as the thermo time switch which controls the cold start injector on jetronic systems.
72 Chevy C10 Stepside 350
90 318is Sold
02 530i Touring Sport
83 E21 320/6 - Sold
84 316 - Sold
85 528i - Sold
Last edited by kenoc; 10-12-2016 at 10:37 PM.