Hello I've got a 1990 Volvo 740 Turbo, it was running great up until a week ago when it started to hesitate on take off. I would give it gas and it would start to bog down and then pick up all the sudden and go. Now it's gotten even worse, and when I first fire it up in the morning it will hardly go past 10mph (bogs and jolts, bogs and jots), once it gets going it'll start to go faster but I still can't get it past 50mph (shifts very late) and it's redlined at that point. As it's accelerating I can hear the wastegate popping and I've never heard that before, it sounds pretty bad. Idles fine, starts perfectly despite outside temperature.

I've tried:

Changing out the AMM with a good one.

Swapped FPR with an old one.

Changed the Radio Suppression Relay.

I pressurized the intake system using the brake reservoir cap and installed schrader valve, seemed to just push air right back out the turbo, so I couldn't tell much from that.


Any Ideas would be awesome, this is really getting on my nerves!!