I have a new crate motor in my 90 lx 5.0. It's been running rough lately. feels like it is missing at lower rpms when the engine is under load. especially going uphill. I replaced the cap and rotor, it helped a little. because i commute 100 miles a day, and premium gas was near $4 bucks a gallon, I had been running regular gas and retarded the timing to 8 degrees so that there would be no detonation. Mpg was around 20 or so, depending.Started running premium now that the prices came down, and adjusted the timing back to 10 degrees, and now the fuel consumption is astronomical. about 7mpg compared to the normal 18-24mpg. Any ideas why it is gulping down the gas? I have a new fangled timing light, an equus model 3568 with digital advance. I had the advance on the timing light set to zero degrees. there were no instructions with the thing. Did I use it correctly? wondering if the readings I get from the timing light are accurate.