Hello all. I am in dire need of some advice about my 97 Volvo 850. It has 98K miles on it and has been doing great until about 8 months ago when the following symptoms started to appear in a gradual manner:

-a small amount of black exhaust
-fuel economy went from about 28 hway to about 20 hway
-a strong fuel smell on the outside of the car after driving
-the biggie: at low speeds/RPMs, the car starts bogging down, almost as if it is about to choke out on me. However, at high speeds, the car runs fine (except for the gas mileage)

These symptoms appear predominantly after a long road trip, say greater than 300 miles. This will be the 4th iteration of my taking it for repairs for the same issues. Here is how the prior repairs played out:

1. replaced the air flow meter (this seemed to fix the problem until I took my next long roadtrip)
2. replaced the oxygen sensor (this seemed to fix the problem until I took my next long roadtrip)
3. This time I took it to a dealer. The fix: excessive corrosion dealing with some connections caused by the lack of some "special" lubrication at those points. (this seemed to fix the problem for the first 15 miles out of the dealer garage)

Any ideas on what this is? The repairs above has cost me 1,200 already. I can't stand much more. Help!!!!!!!!

email me at trasimene73@hotmail.com if possible.

thankfully,
brian