Diesel Bombers - Turbo Overboost troubleshooting

Hey everyone, I know this topic has probably been hammered pretty well, but I am going to start troubleshooting my overboost code and would like to hear some recommendations.

Symptoms: Get turbo over boost code (P0234) when I step into the gas, for instance passing or getting on the highway. Truck goes into limp mode and light comes on. Truck runs fine. Light goes off after 5 starts. No other codes.

I am planning on doing some add-ons in the next 6 months, but before I throw more power at it I would like to get this cleaned up. I plan on doing intake upgrades, exhaust, turbo, programmer, injectors, pump, ect.

I have been all over the web and this seems to be the most knowledgeable forum.

I have read to clean/replace the MAP sensor, check tubing for leaks or blocks, seized wastegate.

Which one should I start with? I looked at the engine diagram for the MAP sensor, but I dont see how to get any tools in there to get to it unless I am looking at the wrong plug. I took a sensor off, which I think is the IAT sensor (facing the engine, on top of the engine just to the right of the valve cover under the fuel rail) and cleaned with carb cleaner. As far as the turbo tubing, I would like to know if anyone has any good tips for checking this because frankly I have no clue. And for the wastegate, I tried spraying it with PB Catalyst to see if it was seized, but I need to find a way to test it.

The truck is stock with 160,000 miles. Runs fine other than that. I have no way currently to test boost and I am trying to avoid taking to a shop because we are saving for a house and I really dont want to spend the money if I dont have to. This is my first Cummins, but I have been a wrench monkey my whole life and dont mind getting my hands dirty.

Any help would be a great help and sorry if this is a mu point.

Thanks
Jake