My wife's 1998 dodge Dakota will sometimes shut down at stop, sometimes hard to restart, other times it will shut down at driving speeds and restart fairly easy ?, and tthen other times it will run fine for 2 or 3 days and again start shutting off ? been told it may be fuel pump, but hate to spend that much $$$ when it could be a relay ?, anyway to test the problem that is less expensive ? no check engine light comes on !
Intermittent problems are tough to know for sure unless there are other related thing you can look at. Otherwise it is just guessing. Dying when coming to a stop could be throttle body coking. Use a scanner and do a minimum idle test. The scanner will turn off the IAC and if the engine dies or the idle goes too low you should look at the throttle body bore and plate to see if it is coked up. Clean, adjust and re-test until idle is at least at minimum idle speed.
dying while driving is another problem (usually) You could look at the fuel pressure. you could look at your fuel trims while you are driving. you could also use a lab scope and look at the fuel pump waveform. But, it could be an intermittent ground or power problem. Fuel pump relay, ASD relay it could even be the computer turning off... you have to catch the problem when it happens to be more sure you can pin it down.