Everybody's Stumped
The car starts fine, and can run a little rough at first but once warm seems to idle fine. When accelerating the car does fine until somewhere around 1500-2000rpm at which time the acceleration drops out. If I back off the pedal and slowly start pressing it again it will accelerate until the same rpm point and then stop accelerating. I have repeated this until I have the car up to 65 miles per hour at which time she seems to run fine. But if I come to a grade, (uphill), she slowly losses speed and won't accelerate until the road becomes level again, at which time she will SLOWLY regain her speed by not pressing too much on the gas.
The previous owner alledgedly switched out the 'throttle body', and the 'computer' with no change, (the old ones were in the trunk when I purchased the vehicle, although I doubt new OEM parts were used as replacements). I figured the previous owner just didn't know what he was doing and was sure my mechanic would quickly diagnose and solve the problem, but so far no results. Before taking it in, I noticed the smell of gas as though the fuel mixture was too rich, also some VERY tiny black bits coming from the tail pipe. Car has no visible leaks
WE ARE STUMPED! Has anyone ever encountered this problem?? Help!

Try changing the fuel filter and see what happens.
Had a similar problem many years ago with my girlfriends' grandmothers' powerglide equipped Chevy V8.
Drove up nuts until we figured out it was a fuel starvation problem caused by the in-line fuel filter.
Easy on the throttle, everything was fine, but give it too much throttle, and it would simply quit.
'Course that was with a carburator, so who knows?

Good luck!

DHG
)
The car starts fine, and can run a little rough at first but once warm seems to idle fine. When accelerating the car does fine until somewhere around 1500-2000rpm at which time the acceleration drops out. If I back off the pedal and slowly start pressing it again it will accelerate until the same rpm point and then stop accelerating. I have repeated this until I have the car up to 65 miles per hour at which time she seems to run fine. But if I come to a grade, (uphill), she slowly losses speed and won't accelerate until the road becomes level again, at which time she will SLOWLY regain her speed by not pressing too much on the gas.
The previous owner alledgedly switched out the 'throttle body', and the 'computer' with no change, (the old ones were in the trunk when I purchased the vehicle, although I doubt new OEM parts were used as replacements). I figured the previous owner just didn't know what he was doing and was sure my mechanic would quickly diagnose and solve the problem, but so far no results. Before taking it in, I noticed the smell of gas as though the fuel mixture was too rich, also some VERY tiny black bits coming from the tail pipe. Car has no visible leaks
WE ARE STUMPED! Has anyone ever encountered this problem?? Help!

Steve


