mixed signals in fuel system

1987 grand am will run and then die after warming up. Seems to have a problem with fuel. Replaced fuel pump, filter, injector, and map sensor. Fan will kick on and off intermittently when vehicle stalls. Thought I had problem solved, but began same thing again. Need to know of any suggestions and ways I should look at to get it analyzed. Seems like it's getting mixed signals about when to ask for fuel, almost like fuel system works when it feels like it. Also vehicle idles very high when in park and neutral, seems to level out when in other gears. Idles where it should be when map sensor is disconnected. TPS was installed last year.

If i remember correctly you had the 2.5 in it right? Here's some things to look into. Check you Gas evaporator canister, it maybe clogged, and if i had to guess it probably has the original filter. If you look in the engine bay, it's right behind the passenger headlight, it's the black round canister, just unbolt it and pull it out, if you have A/c you may have to manuever around it... As far as checking the fuel system, the easiestn way to check it is through the throttle body onto of the engine this way you can tell if you have enough pressure. it sounds too me it maybe more then fuel related though... I think you may have either a vaccuum leak of some sort. replace you PCV valve and see if that makes a difference as well. Keep in mind that it is possible that some of the new fuel system parts are already worn out... good luck...