Here's the tl;dr version: I reset my on-board trip computer and embarked on a 15min journey. At the end of the journey my MPG read 30.0. Accelerating to 2000rpm for <1sec causes the MPG to drop by 0.3-0.4MPG...

Here's the long version: 2002 MCS, stock except DDM CAI, cold plugs and new ignition coil. Using 93 octane gas. I have been concerned at my around town fuel economy for a while. Driving normally (spirited) results in ~16MPG, while driving on the freeway gets a respectable >30MPG.

So I perform a test today, coming home from work I set DashCommand to log and reset the onboard trip computer. It's a 15min journey home, 70% highway. You can see in the attached pic my journey; first low RPM part is my tortuous descent from 10th floor of the garage , high RPM is freeway, last low RPM bit is surface streets to house. I was driving conservatively, never above 3000RPM (I managed pretty well!! ).

By the time I get two stop lights from my house, my MPG is 30, however, I notice that accelerating away from stop lights - 2000RPM for <1sec - results in a 0.3-4MPG decrease in economy - and this after 15mins of driving. This does not make sense to me, and I am wondering if my car is running incredibly rich. Or something???

Couple of other weird things once I looked in ScanXL. 1) I don't see any data from my fuel trim sensors - just the timestamps. Am I doing something wrong? 2) My calculated boost is almost always negative. Is this normal???

Any help/advice greatly appreciated. Looking to diagnose the issue further at this stage. If I can supply other data let me know which sensors to look at.