Spark plug diagnosis?1990 5.0 efi mass air

Just rolled 1200 miles on 5.o efi build and little disappointed with performance.Getting 18 mpg average,but seems like motor wants more fuel/air?Do plugs look lean? All stock lower,addition of gt4o intake,alum. gt40 1.94,175 cfm X heads,headers.New o2s,tps.Was getting detination/popping noise in intake.Went to 91 oct and
seems to have stopped.Runs smooth,no operating codes.This motor is a dog compared to 73 stock 5.0 with 130k!
I do need to change rear gears(2.79) to 3.50 but damn its slow.

 

This chart may help john.. lean look to me , i put 3:25 in my rear made a world of difference

 

Yeh,thats what I was thinking.Had 19# CV 4 hole injectors in,put stock 19# squirters back in today.No improvement.Dont have gauge to check pump pressure.
Could be weak,junk yard unit.May even go 3.73 with the driving I do here.

 

The CV/Exploder 'thin' 4-hole injectors should be a fair improvement, but did you read the datastream, test O2 sensor bias by forcing rich/lean conditions, and does the exhaust have 1/2 to 1 PSI backpressure?

 

Dont think OBD1 will run datastream Andy.If i had VSS hooked up,could run cyl balance KOER.Ran compression test when had plugs out,all good 160/165#.
Went into town today and couldnt get it pop through intake,ran perfect.Had a shop check injector rail presser, good at constant 39 psi.Probably should have invested the 20$ in new gauge for MY tool box..Going to dump codes,drive for a while let it relearn.Hopefully sputter wont return.

 

Ford EEC IV has datastream from '91. I seem to recall, yours was mid-'90s.

 

Oops, I just noted the title of the thread. Which means break out the DVM and start manually checking the sensors one at a time.