97 4X4 Hard start when warm

Howdy all,

My 97 4X4 has been having trouble starting. I recently replaced the ignition switch and did a complete tune up. It fires up fine in the morning when it's cold, or after work when it's been sitting all day. But if I shut it off and run into a store for 10-15 mins, it struggles to restart. It cranks way too many times before starting. I see a lot of posts relating to fuel pressure and thought that may be the problem. But it starts great when cold. I didn't put a fuel filter in when I tuned it up, but I have one now and I'll do it tomorrow. I will also find a fuel pressure gauge. Where is that schraeder valve again? Anybody else have any ideas? Thanks in advance.

What did the tuneup include?

Plugs, wires, distributor cap, rotor, coil, air filter. Also has a recent alternator. They didn't have a fuel filter, but I have since bought one. Haven't had the chance to install it. Could it be a weak battery?
Thanks LT

If you have a voltmeter, go out and measure the battery voltage without the engine running and come back with what you get.

Had a nice multimeter. Loaned it, never saw it again. That was before my tool loaning policy was established. I'll go get it load tested tomorrow after work. I'll let you know how it goes. Thanks