98' Chevy Blazer Cranks but wont Start

You can crank on the key tell the battery dies,...however if i barely turn it to ignition 2 then hurry up and but it on ignition 1 it use to start. Then i had to get it jumped everytime i shut off the engine. Now the only way i can get it to start is to let it set for a couple days,...leave jumper cables on it for about 10-15min.,..and the only way it will start is if the other car is reving on it engine.

When i first got it checked out these were the codes that came up:

po102...maf sensor
po113...intake air sensor
po304...cylinder 4 misfire
po452...po453...and po452 came up again....which they told me that my voltage fuel wasnt getting enough pressure.

Ive bought a new battery, checked the starter and alternator, checked spark plugs(which cylinder 4 is sparking after i lay of the key), wires, distributer cap and rotor. Ive replaced the fuel pump about 4 times in the past 2 years,..however i checked it and it is not the problem.

When i put it on the scan tool yesterday however no codes came up,....I managed to get it started last night, went and got gas,....when the car sat there it started to overheat,....when i left the service engine lite came on and kept blinking at me when i hit the accelorator,...but when i hit the brake it would quit,...as i drove it the temp went down,....however, when ever i came to a complete stop then tried to go,....it would putt along like when u try to put a manual into gear and it about to stall out,.....it never did this to me before,...the engine also sounds horrible while i'm driving now,....

Any advice???