Intermittant hard starting at operating temp

[BSMcCauley]

I never have a problem firing my my 1996 when cold. The "wait to start" light goes out about the time my pre-lube pump has developed 30# of oil pressure, I twist the key and she's running about the time the 2nd injector fires. However, I have been having a more frequent problem with sometimes having having to crank for what seems like forever when the engine's at normal operating temp. Actually, it is closer to 6 or 8 seconds, but when you are used to less than 1, it seems like it's NEVER going to start! If I get too impatient, I can raise the throttle off idle and it will spring to life with a blast of thick black smoke out the tail pipe (immediately dissapearing to normal). Runs just like the day it was new other than the intermittant hard start @ 0 throttle when warmed up. Anyone got any ideas?

Details on the truck: 1996, 4x4, auto, bone stock engine except for the 12V pre/post lube, 202500 miles on the dial. Besides normal maintenance, it's had the thermostat upgrade, KDP secured, recall throttle cable replaced, rubber return hose replaced (cracks caused hard COLD starting problem). Factory Tach indicates about 750-800 RPM at idle whether A/C on and in gear or not. Fuel economy remains 24.5 @ 1500 RPM (ignore the spedo 'cause it's too depressing) or 19-21 @ 70-75 depending on traffic and load. I'm usually empty, it's my daily driver -- 65 miles across Houston twice a day. The truck's got a couple other mods that are not drive train related.