When I bought my N/A 8-valve 745 a couple years back I was getting at least 350 miles to a tank. Now it is more like 250 miles to a tank on a good week. Seems to have been getting gradually yet steadily worse. I realize driving habits affect this, but it has become ridiculous and cannot be correlated with my driving habits. Car has 165K miles and compression in all 4 cyls are well within spec and even. Put in a new timing belt and seals a couple months back...I'm sure the timing isn't off a tooth. There are no FI or Ignition codes being thrown. Starts and runs everytime. You and I both know this car is not a powerhouse, but it is one reliable SOB and I know her well. Her power curve is the same as it was when she ate less gas...she's just eating WAY too much now. I've put a lot of new sensors in, but that is a waste unless they are actually failed (which would usually throw a code). Here are a few things I'd like some feedback on:

1) I put in a Bosch wire set and NGK plugs in when I got the car, along with a new Bosch cap & rotor. Could it be the wires/plugs???

2) I put in a Heavy Duty Mann air filter, which has an additional layer of white matting on it. Could this extra flow reduction cause this?

3) I removed the air-intake preheat mechanism and snorkel. Could it be that it is breathing air that is too hot from inside the engine compartment?

4) Injectors? I've poured everything in the tank to no avail. Thinking about going this route: http://www.fiveomotorsport.com/Injector_SetsSAAB.asp $136 for a set of 4 new isn't bad...and probably cheaper than having my current ones bench cleaned.

I want to keep the car, I put Bilstiens, ball joints, new German brakes and Dunlops all the way around and don't want to lose that investment. Plus, it's a matter of pride. I've done all the work myself and I've done it right...but I surely don't know everything. Just can't figure out the MPG issue.

Please advise.
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'92 745 B230F