I’m more wondering if I’m on the right track here. I have a 98 Buick Century Custom with the 3100 GM engine. For a few years it has had an issue cranking for a long time before it catches and starts. I have cycled the key 3 times before starting it and the issue does not resolve itself, so it does not appear to be a fuel pressure related issue. Just a review of everything that has been done to it: fuel pump changed, fuel filter, fuel pressure regulator, and injectors all changed. Spark plugs and wires replaced. Idle air control valve and air charge temp sensor changed. I’m thinking possibly the mass airflow sensor at this point. Thoughts and advice would be greatly appreciated.

Did you clean the inside of the throttle body where the IAC pintle sits into? If this isn't cleaned, it will prevent air from passing through.

I did not, I’ll give that a shot and see what turns up.

Another way to tell if its IAC related, hold the throttle open just a tad while cranking. If it starts right up and starts to stumble because you let off the throttle, its IAC related.

Did you do anything at all with the TPS?

I replaces the TPS and it made no difference. I do notice a difference when I press on the throttle when starting it, but it doesn’t stumble at all when I let off of it. Other than the cranking, it runs flawlessly.

Cold start. Look at the CTS before starting. Is it reading close to ambient?

If you replaced the TPS, did you install it correctly? I have a video here somewhere that shows the correct installation of the TPS

On cold start, what is the fuel pressure with ignition on and engine not started?

I'm betting it is near zero.

If so, swap the fuel pump relay with something else and see if that fixes it.

If it does, replace the suspect relay.