98 200 Merc Outboard Running Cold

On start up from sitting a couple months, my 98 Mercury 200HP outboard wouldn't come up to temp. I noticed that the tattletale indicator flowed immediately on start up where before it seems there would be a delay (I always thought it ran after the T-stats opened). Checked the T-stats and they were OK (not stuck open) so googled it. After googling it, I felt pretty comfortable it was a Poppet issue so I replaced it. Ran around the bay in it for an hour or so and it still never got to over 100F. Another thing I noticed was that the water pressure seemed erratic. Something else to note is that I had also just replaced the water pump on it. What else will cause one to run cold?

What was the temp before you did all this work? Most temp gages meant for sterndrives don't work well on outboards because they run to cold to move needle off of "C" . The operating temp of that outboard is about 120-125 degrees anyway.

I should have mentioned, I installed a temp gauge for each head, they both always showed around 160 pretty consistantly. The gauges are automotive gauges with a lower temp range.