Buy 2 cans of Brake cleaner(aerosol cans) spray it all around you engine area everywhere you see a vacuum line. All around the intake area. If / where there is a leak, the car will stall. I had a similiar/same thing happening on my 92 400E. After fixing all the leaks, the car began to idle very poor when first started in the AM or after work and them would occasionally surge as you describe at idle or during Stop n Go. I had my injectors "Purged" and that solved my problem(for full details see my post - 400E missing problem fixed). Run better, more power, strong acceleration and No MORE MISS/SURGE
