Okay, I found one problem I caused. When I did the white spacer, instead of filing the spacer I grabbed a washer that was the right thickness & made it fit between the screws, but didnt make it go in the small tube with the spring. SO, I in effect, removed the spacer completely! Waddadoofuss! Anyway, is that a big enough deal to stink up the MPG as bad as 35 MPG? Also, gee this is gonna make me seem REALLY screwy, but, I am gonna suck it up & tell it, anyway.. I( when I was gonna stick the 155 main in, mixed them up & removed the 150, & turned around & RE installed it! I was totally shocked when I saw 150 on the main, but there it was.. Doooh!  Now, Down at the bottom of the tube the diaphragm is on, the slide, there are 2 holes open to the airflow thru the carb throat. Is that correct? I dont see how to do it differently, considfering the orientation of the holes that are there & the ones the screws go thru, seems to be only 1 way to install that plate that sits on the spacer.. SO, should I go with the 150 or the 155/ the plug isnt very dark, thers black sooty stuff on the outside, on the end O the threads, but the ceramic is pretty light, not white, but not exactly a brown or cocoa color.

Nope, Jim, only an empty envelope arrived. I sent it back to ya, with a small check, so you didnt feel ripped off. Dang PO's machine squirted that jet right out the end O the envelope.
Yea, I jammed that plate when I first did the spacer, realized the error & turned it over & around till it fit, My "spacer" had the effect of having no spacer, since it didnt go in the hole the spring goes in, because the diameter was greater than the diameter of the white spacer.