difficult starts-97 Blazer

Hi all!
Got a starting problem.
It’s a 97 Blazer, 4.3 6 cylinder CMFI with about 150,000 miles on it. Bear with me…I’m giving the whole story…

The basic problem is that the starter will operate but will have trouble turning the motor over-but only intermittently. It will start just fine for a week or two, then act up for a few days. When it’s acting up, the engine will crank eventually but takes a few seconds.

This began last October. I replaced the battery, thinking maybe it wasn’t delivering enough juice and since the truck still had the original starter, I replaced that too. Worked fine for a couple days, but the original problem came back for about a week. I checked the battery cable and every ground I could locate and load-tested the battery & could find nothing wrong. The problem went away for several months. Acted up a couple times in February, once or twice in April and worked fine up until last week when the same thing started happening.
The other day, a new problem came up: When I turned the key to “on” (not to crank position) the gauges wouldn’t move and I didn’t hear the fuel pump energize. I tapped the gear shift once and it worked/started fine but I think that was a coincidence because it only worked one time. Otherwise sometimes the gauges and pump would work and othertimes not.
So….knowing that the 97’s have a problem with ignition switches, I replaced that this past Friday. (Third one that this truck has had over the years). That seems to have fixed the issue with the gauges and fuel pump starting. Also, the fuel filter was WAY overdue for replacing, so I put a new one in yesterday.
Now I’m back at the original problem though. Intermittent hard starting. The fact that I do hear the pump with key on tells me that the relay is working (I think) . I’m off to the store now to see if I can get a fuel pressure gauge to see how much pressure I’m getting.
Any ideas on what else it could be?

....When it’s acting up, the engine will crank eventually but takes a few seconds....

Does it take a few seconds for the starter to turn the engine over? Or does it take a few seconds for the engine to run while the starter is turning the engine over?

Thanks for the help...I see you answered my fuel pressure question as well.

To answer on this one, when it chooses to act up, I hear the starter going and it's a few seconds before the engine itself cranks. I initially thought there wasn't enough power to the starter, but now I'm wondering if the engine is getting fuel, which is what prompted my other post about fuel pressure.

Thanks,
-Mike

Low fuel pressure and/or excessive leakdown will cause extended cranking times before the engine starts.