1997 boxster warm start problem

[STYLUS]

New to this site hoping to find help with a very frustrating no start w/ warm problem. Any information, or ideas will be much appreciated.
Events of the past 3 weeks:
1) i replaced water pump 3 weeks ago. Took all steps to restore cooling system. Cools perfect (185). But, left damaged plastic shield off to replace later.

2) boxster ran perfect. Then, last week would crank and not start. Restarted and ran fine after cooled for 45 min. Since then this problem is predictable.

3) first start. Boxster always starts and runs perfect. After reaching operating temp, it will turn over but will not start. After 45 min or so, it will start and run fine. Have noted that if the engine is not cooled down enough (30 min or so) it will start but run rough w/ a slight mis firing feel and sound. Will run if it stays running at high rpm for a min or so, then it will run fine. Again, when engine is turned off after a short run, it will start perfect but after it sits for 15 min, will not start until cooled (45 min or so).

4) slight fuel smell after restart problem at traffic light.

5) code at independent shop today po102 mass flow sensor low input.
Recommended replacing crank angle sensor/mass air flow sensor.

Wondering which sensor that i should replace first with the clues above?
Also, 08/08 previous owner had boxster scoped w/porsche pst2. Results were fault code 02 sensor cyl 4-6, 02 range cyl 1-3. Do not think that this work was done. And, would this cause a no warm start problem?

With the mis fire sound when first starting after a cool down period, would a mass flow sensor be the first to replace? Would a crank angle sensor act this way after a cool down start?

Any help, or ideas will be much appreciated as i am loosing sleep on this one...hard to figure.

Will a porsche pst2 zero in on a crank/air flow sensor problem? Piwis? Thinking i need at least a durametric???