getting frustrated

[Jim & Michelle]

Well I've checked for vaccum leaks, replaced air hose at intake (it was in really bad shape), replaced one small vaccum line at turbo that was dried out but didn't seem to be leaking.  The car started up good but still had a miss in it.  I drove it down the street and back about a half mile accelerating slowly it was running fairly well, I pushed harder on the gas and the car began to miss badly almost to the point of dying, after getting back I ran a code check even though the check engine light  didn't come on, code was 2113 so I put a new dist in since the connector at the dist was dried and cracked.  I just knew that was the problem.  Well It didn't seem to help and I still get the same code.  the engine will run o.k. for about five minutes or so and then began to miss, the engine will rev up fair when not under a load, but put it in drive and hold the brake and it doesn't want to run when throttle is pushed.  The longer the car idles the worse it runs untill it dies, also the longer the engine runs the louder the fuel pump seems to get,  the pump has been changed,  filters been changed,  I haven't checked fuel pressure one of the machanics I had it to supposed to have checked all that.  I thought at first it was in the firing, but I'm beginning to think it's in the fuel system.  What might be somthing else I should check?  It gets to the point while idling that it won't even rev up it just dies, starts back but barely runs.  To sum it up it starts and runs fairly good for about 5 minutes and down hill from there oh yeah it's a 1988 5kt.  One more question, what is the electronic box and pump under the rear seat for?  Jim