Gas mileage

[rayskr]

I've had my '87 GN for 12 years. I used to get 18-22 mpg, city and highway. For the last year or so, I've gotten 10-12 mpg. Basically stock, cold air, TT93 chip, LS-1 MAF/Translator from Full Throttle, set at zero and zero, per specs., Walbro pump w/ hot wire, vacuum brakes. Car runs well, no black smoke, but smells a bit rich on start. Before the LS-1, I had a rebuilt MAF for a year and mileage was same as now. a few years back, I replaced coil pack and Modulator. Pulled a plug recently and it looks "normal". Car runs fine, except idle is a bit rough and even sounds like a sporatic miss. Unfortunately, I don't remember when this actually started. Here are the Numbers.
Key on, not running; tps=.44, 4.7,
Idling in park @ 165 degrees; BLM=119, INT=128, IAC=18/22, tps=.48, O2Volts=.51/.57, O2 cross=.027, adv=37 deg., LV8=039, MAT=091, MAF=007, INT=128, open loop, rich/lean switching
Anybody have an idea?

 

[Buckshot G/N]

Rayskr, I'm in the same boat ,but my mpg drop to about 13-15 I have been burning 100% sunoco gasoline,it has help a tad,maybe we will get some help.Plugs an maf are fine.....SOS....

 

[buckbuick]

i was getting real bad gas mileage until i turned my fuel pressure down to about 30 pounds it also runs better now,i know they say you should run at 42 pounds but that was way to rich for my car.just something to try.