Ipswich Town were beaten in stoppage time as Joe Nuttall won it for the hosts in stoppage time.
The game has been drifting towards a draw after Kiernan Dewsbury-Hall had fired Blackpool in front, after defensive errors had given the hosts possession in a dangerous position, before Freddie Sears first goal of the season levelled matters.
The Blues probably had the better of the game and better of the chances, but once again weren't able to take them when they came as Flynn Downes, Sears and Alan Judge all had opportunities drift away.
The sting in the tail came in stoppage time, when Nuttall met a late cross at the near post as he beat keeper Tomas Holy to the ball to head home.
The Blues remain outside the play-off places heading into Tuesday night's vital clash with Fleetwood at Portman Road, after the Blues failed to take advantage on an afternoon where Rotherham, Peterborough, Wycombe and Oxford all dropped points.
With Kayden Jackson (suspended) and James Norwood (injured) unavailable, Lambert made four changes to his side as Freddie Sears, Teddy Bishop, Emyr Huws and Cole Skuse all came into the side, with Jon Nolan, Alan Judge, Gwion Edwards and Jackson dropping out.
The hosts made the early running, with Town needing to deal with three early corners inside the first two minutes, before the first opening for Lambert's men seeing Sears latch onto a ball over the top and lash across goal, only for the on-running Huws to miss his connection by inches in front of an open net.
Ipswich were beginning to get a foothold in windy conditions, with another decent move seeing Flynn Downes drive through the middle of midfield before laying off to Will Keane, who dragged wide.
There was little between the two sides during the first 25 minutes but the scoreboard soon showed differently, with Ipswich the architects of their own downfall as they fell behind. It started with Luke Garbutt, who tried to be too clever in the defensive third with an attempted flick between his own legs which gifted the hosts possession, before Downes and Huws got in each other's way and lost the ball again for Dewsbury-Hall to bend home off the post.
The chance to respond soon came when good work from Keane opened up the Blackpool defence for the on-rushing Downes, who had time to steady himself but saw his left-footed shot saved by Chris Maxwell. Sears looked to gobble up the rebound but wasn't quick enough to get a clean shot away, with Calum MacDonald playing the ball off him for a goal kick. Town wanted a penalty but there was nothing doing.
Sears had a shot saved by Maxwell at the end of the opening period but, within 10 of the second kick-off, he'd found the net. Keane's composure made it as the striker kept his nerve, held his cross after being freed to the right of the box, and eventually chipped the ball back into danger for Sears to finish back across the goalkeeper and into the net.
Downes picked up his 10th booking of the season, which will now see him missing the visits of Fleetwood and Coventry, just seconds before he and Teddy Bishop were replaced by Dobra and Alan Judge as the Blues hunted a winner.
Both sides traded blows, with Judge firing wide and Gary Madine heading a corner against the bar and Lambert sending on teenage striker Simpson for his league debut, but ultimately neither side could find a second goal.
That was until stoppage time when, seconds after Sears had missed a one-on-one, Nuttall headed home to send the home fans wild and leaving away supporters with their heads in their hands once again.
Blackpool: Maxwell; Turton, Moore, Husband; Dewsbury-Hall, Virtue, MacDonald; Feeney, Ronan (Nuttall, 67), Delfouneso, Madine
Subs: Sims, Howe, Bola, Edwards, Spearing, Ward
Ipswich Town: Holy; Woolfenden, Chambers, Earl, Garbutt; Skuse, Huws, Downes (Judge, 60); Sears, Bishop (Dobra 60), Keane (Simpson, 84)
Subs: Norris, Wilson, Nolan, Edwards
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