Cadillac Repair: 1991 4.9 deville, great shape, fuel filter

Question
Hi Kevin, I'm puzzled. My 1991 Deville with 125K Is bogging out during acceleration. Sometimes it will run better than others but always has some sort of hesitation. On occasion when you first start the motor it will back fire and smoke from the air intake on the front of the grill. In addition it seems to hesitate more at when i apply slower accelerating. I have spent well over $2000 trying to rectify this problem to no avail. These are a few of the repairs that have been done:
1* Sending unit
2* Fuel Pump
3* EGR Valve
4* Plugs and wires
5* Rotor and Distributor
6* Fuel filtered

Back in December I had the fuel system cleaned and a new fuel filter installed, it ran much better for 1500 miles or so but now is back to its old ways. Kevin, My Caddy is in great shape other wise, I would hate to get rid of it. Any suggestions?
Thanks, Keith


Answer
Keith,
Hate to say it but I'd probably try another fuel system flush. If that fixes it again, start looking at the tank for sort signs of contamination. I'd also want to see what's inside the fuel filter. Could give you a clue about what's going on. Also, any chance the gas station you use is the problem?