1999 Chevy Suburban won't slow down.

I have a 1999 Chevy Suburban with the 5.7 liter motor. When I let off the
gas, the truck doesn't slow down right away, it kind of coasts as if you shifted
it into neutral, and then somewhere between 3 and 10 seconds you feel the
back pressure and it starts to slow. I can have the gear shift in any position,
D, 3, 2, 1 and it acts this way.

If I disconnect the Throttle Position Sensor (TPS), the issue goes away.
When you let off the gas, the truck starts to slow right away, like a normal
vehicle. However, running with the TPS disconnected causes bad things and
so it's not a long term fix. I've replaced the TPS with a known good one and it
drives the same.

A neighbor has an identical truck and it does the same thing. His has over
200k miles and it's "..done it forever, I think since new." Mine has low miles
but I haven't had it since new but it's done since I've had it.

What's causing this and what's the fix? Dealerships tell me it's the way it's
designed, nothing can be done. Some people say I need a new "chip" that
will give more power and will fix it but they can't tell me why so I'm not so
sure they know.

Thanks