Starting issue when not 100% cold, enginge stops uphill

[TrondAM]

For the last weeks I've had an issue starting my Toyota Corolla 1.4 D4-D 2007 90Hk.

When engine was cold / not used for several hours it would start instantly (1-2s), but when warm (even only after a 10minute drive) it could take 5-6secs or more if driven for a longer duration.
Start motor made the same sound in both cases. No issue once the engine was running. Since the Battery was old I decided to change it, afterward the start motor sounded like it had more rpm, but still took more time to start when warm.

On thursday I did a longer ride (320km, 4h 30min). Stopped after 2h, major problems starting after 10min stop. Needed multiple attempts at 10-15secs each before the car finally started.
1km before the destination when I drove off the highway the car suddenly stopped uphill. After 10minutes I managed to start it after several long attempts, but this time the engine warning light was lit. I got the error code read and it said P1229 rail pressure. 

On friday the car started after 1-2s in the morning, but after that it used 10-15secs to start, and I experienced three instant engine cutoffs during the day (manage to get it started after several long attepts) all when giving some extra power when starting climbs uphill. I did manage to drive the 320km home though since the car had no issues once running on the highway and I attempted avoiding stressing the engine.

Today the engine started normally after 1-2s the first time this morning, I drove 10minutes, but after being stopped for 3hours it still took 3x10secs attempts before starting....I highly doubt the engine was warm after 3 hours...

Going to have the guys at the local garage take a look at it on wednesday... I believe it is either two separate issues, or (which I believe) one common issue both the starting and the engine cutoff, since the engine cutoff first occured after the start issue escalated.... Kinda hoping it is something "simple" like a sensor or the diesel filter (thinking about changing it myself tomorrow).

I've tried to search online, but there are so many different suggestions to similar issues.... diesel filter, air sensor, temperature sensor, injectors, egr sensor... diesel temperature...leaks in hosing return line betweeen injectors. Anyone who want to guess? 🙂 Hopefully I get a clear answer on wednesday, but not 100% sure...

First two weeks:

-Normal start when cold, longer when warm engine.
-Start motor made the same sound in both cases

Last days:
-Normal start first start of the day
-Major issue starting afterwards, no matter the duration of the drive or being stopped for several hours.
-Start motor sounds the same in both cases
-Engine cuts of instantly under heavy load going uphill (If in third gear, not experienced yet in second), engine warning lit afterwards, P1229 rail pressure

Car has 191 000km now, injectors was changed at 150...