Running rough and not able to scan codes

[bschoole]

I have a 99 (late 98) discovery I, 145k, 100k on engine. A couple of weeks ago I took the truck out after it had been sitting a while. It started up, and I noticed after putting it into gear it had lost a lot of power. I drove it around and it started sputtering and then all of a sudden stopped, cleared up, power was back. Next time I drove it same thing. Next time I drove it, it just stayed running bad. I can go with it, but if you give it to much gas it starts stuttering, rpm's dropping and rising. If you slowly give it gas and manually shift it through its gears I can manage to drive it. It idles at correct speed although a little rough, and I can get the rpms up so don't think its VSS. I replaced coils (with known good working ones), wires were replaced less than year ago, replaced spark plugs with NGK coppers. Replaced fuel filter. Still running crappy. So I am looking for advice on that. Tried to get codes read, obd II scanner wouldn't read at all. Searched the forums and found this ... "anyways the power for the OBD2 connector is from the security module, I am pretty sure everything else is either direct grounds or ECU wires. I would check power and ground on the connector first. When I first bought my truck the security module fuse was removed (aftermarket security was installed) and I had no power at the OBD2 port, I wired power directly to it, then after reading the rave manual schematics I found and repaired the actual problem" My truck has aftermarket remote starter (bought like that) so I am thinking the stock security system is disabled. How would I wire up power directly to try and get codes. I have "repaired" my ECU once when after a heavy rain storm it wouldn't start, the box had corroded, so I cleaned up the board and sealed the box again so I don't think its that. Any help is appreciated, I am trying to fix this thing up so I can sell it.

[Disco Mike]

Do yourself a big favor and remove that remote set up, they always screw up our trucks.
As for the codes, check and make sure all your fuse under the hood are good.

[ihscouts]

Data Link Connector (ODBII port) is powered by the 10A F3 fuse located in Satellite Fuse Box 2. That's under the steering wheel.