Chevrolet Repair: 91 s10 blazer wont start

Question
ok here goes. I purchased a 1991 s10 blazer 2wd 4.3 tbi auto. I drove it about an hour and a half from where I bought it to where I live. I noticed that it idles quite high. first chance I got I brought it to a mechanic to see why it idled so high. the gasket under the tbi unit was broken and leaking. I purchased one and replaced it. after that it ran very poorly. so just for good measure, figuring it couldn't hurt I put new plugs, wires, dist. cap and rotor button on it to see if that helped. it didn't. so I replaced the coil. that didn't make any difference either. I have checked for spark. that seems to be good I removed the breather and the metal ring under it and the injectors seem to be pulsing like they should. the fuel pump comes on for the two seconds like I read it should when you first turn the key to on position. have tried cycling the key off and on for two seconds a few times before trying to actually start it. was told that was a way to check if the fuel pump was weak. didn't make a difference. pulled the plugs they were wet with fuel. while cranking it didn't belch through the tbi but when I let off it does. it lets out a big puff of white smoke that smells like gas. I have no way of checking fuel pressure or for checking codes. and I have checked and replaced all of the vacuum lines on entire engine. PLEASE HELP!!!!!!

Answer
HI JEREMY,,WELL THIS SEEMS LIKE A RICH CONDITION FOR SURE..I WOULD NOT WASTE YOUR TIME CHECKING FUEL PUMP PRESSURE BECAUSE IT SOUNDS LIKE IT IS MORE THEN OK..BUT WHEN YOU SAY IT RUNS POORLY DO YOU MEAN IT IDLES POORLY OR RUNS POORLY ON THE OPEN ROAD..IF IT RUNS OK ON THE OPEN ROAD AND IDLES BAD LIKE LOPING OR HUNTING,UP AND DOWN NOT SMOOTH..IF THIS IS THE CAUSE THIS MAY HAVE A BAD MAP SENSOR...TRY TO REMOVE THE WIRING HARNESS TO IT AND SEE IF IT IDLES BETTER. NOT PERFECT BUT BETTER. IF SO IT IS BAD. THE OTHER POSSIBLE PROBLEM COULD BE THE OXYGEN SENSORS ARE BAD...THIS WOULD ALLOW TO MUCH FUEL TO COME INTO THE INJ'S..THE PULSE TO THE INJ'S WOULD BE LONGER I MEAN.. TRY TO UNPLUG THE OXYGEN SENSOR AND SEE IF THIS HELPS IT. IF YOU COULD SCAN THIS WITH A PRE OBD 2 SCANNER IT WOULD HELP ME A LOT TO KNOW WHAT IS GOING ON WITH IT..BUT I UNDERSTAND YOUR PROBLEM.....THIS SHOULD KEEP YOU BUSY FOR A WHILE GET BACK TO ME WITH MORE INFO OR YOUR FINDINGS..GOOD LUCK TO YOU,,,TOM..