Write-ups from the manuals and the garage. Every one starts with the symptom, works to the root cause, and tells you what to check before you spend anything.
Starts fine cold, cranks forever hot. The fault is lost rest pressure. Diagnostic order, cheapest check first.
Before you touch the engine, look at your dashboard. If the ABS light is on too, you have one fault — not two — and it's probably a one-dollar fuse.
More write-ups in progress — E30 rough idle and Motronic diagnostics.