If your exhaust isn't visible at wide open throttle land and adjust the highspeed needle. A couple of clicks richer is what you want.

The glowplugs you got with the plane came in individual packages, unopened, right? If they were used, all bets are off.

Try a new OS#8 and a good highspeed needle set.

How to adjust the HS needle on the ground:
With a warmed up engine at WOT, slowly richen until you're absolutely positive the engine is running too rich. It's easy to tell. It was screaming and richening slowed it down.
Now slowly lean the needle.
It will speed up (or you were wrong about it running too rich).
It will continue to speed up as you lean it out.
After awhile it will start to slow down. You've just found out where the "way too lean" setting is.
Quickly turn it back out richer 3 or 4 or 5 clicks.
If you can see the exhaust has a touch of smoke, fly it and look for exhaust in the air. If none, land right away and richen a couple more clicks and go back up. You ought to be close to a good setting.

Every takeoff, look for a bit of exhaust. Anytime you see none, the atmosphere that day has changed enough that you need a click or two richer. It's usually a cooler day than the last you flew.

As the days get warmer, your setting is going to get richer from session to session.
As the days get cooler, your setting is going to go leaner from session to session.
Most sessions won't show any change if you're flying often.