My car wants to stall in 5th (help)

[matt l]

Basically my car has never really felt right since being into seat but its been on the rollers at ptorque again and actually made 5bhp more than it did before it went into seat but i have noticed recently that in 5th gear @ 1250-1500 revs (roughly 40mph) if i let off and press the accelorator again then it shudders alot and feels like it is dying to stall on me and will until i either drop down to 4th and go quicker yet if i drop to below that so doing around 30/35 in 5th then its fine doesnt want to stall at all and if i go above 1500revs its fine its very strange as like i say it is only in betweem 1250 and 1500 revs

anyone known anything like it?

Matt

edit: its a mapped pd100, and went into seat for aload of suspension bits changed and a a vaccum pipe that had split.

 

[scoobsta1990]

that could be anything really, could be something in the map, injector on its way out, could be they haven't put the vaccum pipe on fully, also they could have dislodged something while doing the work, id take it back and get them to road test it with you in the car so you can show them what it does.

 

[zach225]

I agree,

does also sound like it could be flywheel judder