I've got a 91 Deville with 210,000 kms whatever that equates to in miles, and it runs fairly well and all, tuned up correctly, but at WOT when the engine is warm it wants to give out. I changed the fuel filter, checked the pressure which is between 38 and 42 PSI, cleaned the throttle body, changed the TPS (now has a new one), new cap and rotor, good plugs and wires, and I'm stumped. It's smooth by crusing speeds but when I want to accelerate sometimes I can hardly get it up to 50 MPH, unless I let off the gas a bit then it begins to pick up speed- slowly. When floored, it surges- all of a sudden wants to go but then nearly stalls. It keeps doing this and I can't figure out what's wrong- until I change my head gaskets on my 97 Eldorado, this is my only form of transportation and I don't want to end up stuck somewhere.
Any ideas on what's causing this problem at WOT? All comments are welcomed.