Car stalls out and hard to restart

It's not hard to say without a check engine light. If you test the vehicle when the problem occurs, you will clearly see if it is lacking fuel delivery or ignition spark. From there, utilizing the shop manual, wiring diagrams, a voltmeter / ohmmeter -- you can trace down the failure to the component at fault. Throwing parts at the vehicle to try and repair it hasn't worked thus far, and is consistently a bad idea. Imagine if you had paid $120 even for a diagnostic test that got you the answer you needed. Would that be cheaper than a fuel pump and filter and idle air control valve? Just suggesting that a professional diagnostic opinion is quite worthwhile.