Started about year & 1/2 ago at 175 k.
I put in Standyne injector cleaner in tank and smoke went away for 5k. After a few K more smoke I tried Standyne again. No help.
Filled new fuel filter with Seafoam injector cleaner, let idle 3 mintues, shout down for 15, then drove like I stoled it for 30 miles. Per Seafoam instruction. No help.
Added 8 onces of Standyne to tank of 5 gal. Then 8 onces to last 2 gal. Ran till had .45 gals left. NO HELP.
Smoke did not look never blue in beginning but now does look blueish. After idling at light for 30 seconds it smokes bad at first leaving light.

Injector or is there other things?

PS truck bone stock, never uses oil. Runs fine.