Mazda B4000 starting and first-gear probs

I have a 2000 Mazda B4000 with 2 little problems I don’t know anything about. First is when I go to start the truck it takes a long time to turn over. A friend of mine said that a valve is not maintaining fuel pressure so the fuel is not sitting ready for the starter when I go to start up. But if i engage the key for a few seconds and time it right it will turn over easily (apparently allowing the fuel pressure to build to the appropriate level). Is this a little valve or gasket or something I can replace to maintain the pressure?
Second, when I’m coming from a stop or accelerating out of a slow roll there is a ‘shudder’ or ‘shiver’ in the drivetrain that almost feels like the shift from 1st to 2nd is just kinda lumpy. It also happens if I come to an abrupt stop, so gearing down into 1st. It doesn’t feel like something that is getting worse, but I don’t want it to be causing damage or have my driveshaft snap or something.
Other than that this truck seems really well maintained by the previous owner, and a mechanicly inclined friend of mine said everything else looks

You might cycle the key on and off several times before cranking the engine, and look forward to replacing the fuel pump soon, most likely.

I’m not sure you are speaking of an automatic but if you are and haven’t had the transmission serviced recently doing so might clear up the problem as it sounds like the lock up clutch is not releasing properly.

You could have a bad fuel pressure regulator, but I suspect your fuel pump may be on its last leg as well. Check your fuel pressure with a gauge and see where it stands.