Starting issues

Spraying Carb cleaner through an injector isn't the best idea. There's a very good chance you'll make the problem worse. Please, please don't go "listening" to your injectors with a screwdriver. You aren't going to find anything. If an injector is bad enough on the Riv to "sound" different, it'll set a code.
However, leak-down cannot be detected by the PCM.

Do this......
Hook up your FP gauge and prime the fuel rail. Record the pressure. Go in the house, do whatever for 15 minutes. Go out and record the pressure again. Repeat this step for about 3 hours. See how far the pressure drops in that time. If the pressure is down, you have a leaking injector.
At this point, if you're mechanically inclined, relieve the pressure in the rail, and remove it from the car with the injectors still attached to it, but leave the fuel lines attached. Disconnect all electrical connectors from the injectors (so you don't spray fuel everywhere). Prime the fuel rail again (key on). Tie off the rail to the hood or something and let it hang. This way, you can visually see which injector is leaking. If/when you find it, it's just a matter of removing the CPA, and replacing the injector.

Removing the rail on the Riv is easy. You just have to be careful with the plastic fuel lines.

Thanks Scott that is definitely do-able as I had to remove the rail to replace the Intake manifold gaskets awhile back. The only difference is, back then, I removed the plastic fuel lines first so I wouldn't pinch them, so that would be the only thing I'd be worried about especially now that the weather is getting cold. What is the CPA?

Unfortunately the FP gauge was a rental so I will have to acquire it again soon to do the test.

Thanks for all your help and info, will try this the first chance I get. But can you clarify my question above about whether our cars slowly build up fuel pressure at first start up of the day or should it always be immediate?

CPA = Connector Position Assurance.

Sorry for that. I refer to everything as a CPA that holds something in (clips, pins, etc). The little tabs on the fuel injector clips that you have to pull out first before you can squeeze and remove the connector... That's a CPA. It's nothing more than a lock so that the connector cannot accidentally fall off. MAF sensors and what-not have them (usually gray). The ones I was referring to are the metal "horseshoes" that hold the injectors to the rail on the top end.

The FP, on initial key-on, will prime right up to 50-55psi. It's not really a BAM 50psi. It'll start out slow, then usually ramp up fast once the pressure builds up past 10psi or so. The whole process takes about 1-2 seconds. Now, if the fuel happened to bleed off into the tank overnight, it would take a little longer for the pressure to build in the morning (lot more line to fill). This wouldn't result in any abnormal running conditions, but the engine may have to crank for an extra second before the car actually starts.

You've been a great help man, when I get this resolved, I will post my results,