what is missing from glow plug test?

[hardtime]

99 f350 still starts hard if any at all in the 20s. on first check gpr. was bad. replaced it with $20 cheapie and 2 new batts. Trucks fires right up. later go out to find dead truck. Cheapie relay sticks on and drains batts. replace with nappa $80 relay and charge up batts. Truck starts hard and blows white smoke.
check gp's only 1 on left bank ohms @ 1.5 and 3 on right bank ohm @ 1.2

Can anybody offer any advice if there is anything ELSE i can check to be SURE it is just bad gp's ie, pcm, gpcm. What can i do to be sure, what to look out for, oh and how do i check fuel heater in fuel filter?

thanks for all help past and present, you guys are awesome

[adfields]

Bad glow plugs would make sense if they were stuck on. They should never be on more then 3 or 4 minets at a time, or they can burn out. I have never used an ohms meeter on them, I just use a test light and if it lights good then the glow plug is good.

[hardtime]

thanks for your opinion adfields i will double check with a t lite, can anyone way in here with some serious advice and or DIRECTION.