1994 Ford Aerostar van when in overdrive runs rough, like its not running on all cylinders but at lower speeds runs ok

It can be issue with low fuel pressure,the fuel pump is getting old both needs to be checked.Also get the IAC valve checked.
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These details will help.
Thanks.

some fault codes stored in your car,
use autocom cdp pro cars check your car and clear the fault codes.

1994 Ford AEROSTAR Recall ID from NHTSA: 99V028000 Auto Recall Date: 02/09/1999
Vehicle Component: ELECTRICAL SYSTEM:WIRING:FRONT UNDERHOOD
Estimated Vehicles Affected: 23097
1994 FORD AEROSTAR Defect Summary:
VEHICLE DESCRIPTION: MINI VANS. HEAT GENERATION IN THE WIRING HARNESS TO THE FUEL PUMP/SENDER ASSEMBLY CAN CAUSE AN ELECTRICAL SHORT. THE VEHICLE COULD EXPERIENCE A LOSS OF POWER AND BECOME IMMOBILIZED AND THE FUEL GAUGE MAY BE ERRATIC.
Defect Consequence:
HEAT DAMAGE, INCLUDING MELTING OR CHARRING OF THE FUEL PUMP AND SENDER ASSEMBLY WIRE HARNESS AND ASSOCIATED WIRING HARNESSES CAN ALSO RESULT. THE SHORT CIRCUIT COULD ALSO HAVE THE POTENTIAL FOR A VEHICLE FIRE.
Remedy:
DEALERS WILL INSTALL A FUSED JUMPER HARNESS IN THE FUEL PUMP GROUND CIRCUIT THAT WILL BE INSTALLED AT THE FUEL PUMP INERTIA SHUT-OFF SWITCH.
Notes: FORD MOTOR COMPANY, 99S01 1994 Ford AEROSTAR Recall ID from NHTSA: 97V204000 Auto Recall Date: 11/13/1997
Vehicle Component: POWER TRAIN:TRANSFER CASE (4-WHEEL DRIVE)
Estimated Vehicles Affected: 75000
1994 FORD AEROSTAR Defect Summary:
VEHICLE DESCRIPTION: ALL WHEEL DRIVE PASSENGER MINIVANS. THESE VEHICLES CAN DEVELOP POWERTRAIN BENDING RESONANCE OR TRANSFER CASE OUTPUT SHAFT BUSHING DISPLACEMENT. THE POWERTRAIN BENDING RESONANCE OR THE OUTPUT SHAFT BUSHING DISPLACEMENT CAN RESULT IN STRUCTURAL FAILURE OF THE TRANSMISSION AND/OR TRANSFER CASE. FLUID EXPLUSION, DRIVESHAFT SEPARATION OR LOSS OF VEHICLE DRIVE CAN RESULT.
Defect Consequence:
THIS CONDITION CAN CAUSE A LOSS OF VEHICLE CONTROL, AND, IF THE EXPELLED FLUID CONTACTS THE EXHAUST SYSTEM, A VEHICLE FIRE COULD OCCUR.
Remedy:
DEALERS WILL INSTALL A NEW TRANSFER CASE REAR OUTPUT SHAFT BUSHING AND AN ALUMINUM DRIVESHAFT WILL BE INSTALLED.
Notes: FORD MOTOR COMPANY, 1994 Ford AEROSTAR Recall ID from NHTSA: 99V029000 Auto Recall Date: 02/09/1999
Vehicle Component: ELECTRICAL SYSTEM:IGNITION:SWITCH
Estimated Vehicles Affected: 762201
1994 FORD AEROSTAR Defect Summary:
VEHICLE DESCRIPTION: MINI VANS. THESE VEHICLES WERE PRODUCED WITH A HIGHER THAN SPECIFIED ELECTRICAL LOAD THROUGH THE ACCESSORY POWER FEED CIRCUIT. THE POTENTIAL FOR CONTACT BETWEEN THE B2 (BATTERY), A2 (ACCESSORY), AND P1 (PROOF) CIRCUITS CAN OCCUR, CREATING A SHORT CIRCUIT, ALLOWING CURRENT TO FLOW THROUGH THE GROUND WIRE.
Defect Consequence:
THIS CAN CAUSE OVER HEATING AND THE POTENTIAL FOR A VEHICLE FIRE.
Remedy:
DEALERS WILL INSTALL A JUMPER HARNESS WITH A RELAY WHICH WILL RE-ROUTE AND ACTIVATE ALL A2 ACCESSORIES THROUGH THE RELAY.
Notes: FORD MOTOR COMPANY, 99S02 1994 Ford AEROSTAR Recall ID from NHTSA: 98E010000 Auto Recall Date: 04/08/1998
Vehicle Component: SERVICE BRAKES, AIR:DISC:ROTOR
Estimated Vehicles Affected: 23500
1994 FORD AEROSTAR Defect Summary:
EQUIPMENT DESCRIPTION: AFTERMARKET BRAKE ROTORS FOR USE ON CERTAIN FORD AND MAZDA TRUCKS. CRACKED CASTINGS CAUSED CRACKS TO APPEAR ON THE OUTER DIAMETER OF THE ROTOR HAT OR AROUND THE STUD HOLE.
Defect Consequence:
LOSS OF BRAKING CAN RESULT.
Remedy:
AIMCO WILL REIMBURSE CONSUMERS/INSTALLERS FOR THE COST OF REPLACEMENT ROTORS AND INSTALLATION. CONSUMERS ARE REQUESTED TO RETURN TO THE LOCATION WHERE THE ROTORS WERE ORIGINALLY PURCHASED/INSTALLED FOR REPLACEMENT.
Notes: AIMCO PRODUCTS INC., 1994 Ford AEROSTAR Recall ID from NHTSA: 06E022000 Auto Recall Date: 03/13/2006
Vehicle Component: SERVICE BRAKES, HYDRAULIC
Estimated Vehicles Affected: 7440
1994 FORD AEROSTAR Defect Summary:
CERTAIN AFTERMARKET BRAKE HYDRAULIC MASTER CYLINDERS SOLD AS REPLACEMENT BRAKE CYLINDERS FOR CERTAIN FORD, DAIMLERCHRYSLER, AND JEEP PASSENGER VEHICLES. THESE BRAKE CYLINDERS WERE SOLD UNDER THE BRAND NAMES OF NAPA, RAYBESTOS, AIMCO, AC DELCO, CARQUEST, BENDIX, AND WAGNER. ONLY PRODUCTS THAT WERE MANUFACTURED FROM JULY 27, 2005 THROUGH JANUARY 17, 2006 (DATE CODES 0529 THROUGH 0602) ARE SUBJECT TO THIS RECALL. WHEN SUBJECT TO VERY COLD TEMPERATURES, AN INTERNAL SEAL IN THE MASTER CYLINDER COULD LOSE FLEXIBILITY AND MAY CAUSE BRAKE FLUID TO LEAK.
Defect Consequence:
LOSS OF BRAKE FLUID CAN LEAD TO A DECREASE IN BRAKE LINE PRESSURE AND AN INCREASE IN STOPPING DISTANCE, WHICH CAN RESULT IN A VEHICLE CRASH.
Remedy:
AFFINIA (BRAKE PARTS, INC.) WILL REPLACE THE SUBJECT BRAKE HYDRAULIC MASTER CYLINDERS FREE OF CHARGE. THE RECALL BEGAN ON MARCH 20, 2006. OWNERS CAN CONTACT AFFINA GROUP CUSTOMER SERVICE AT 1-800-323-0354.
Notes: BRAKE PARTS, INC

maybe if it is electronic overdrive

try these website to see if they have you van listed it www.autozone.com and the other one is www.alldatadiy.com if they have your van listed and another thing you can do is stop by your local library and get your hands on a Haynes auto repair manual for your van

Go to www.autozone.com and register for free.
Now you can view a full free online repair manual for your van.

overdrive vacume hose may be off.

Do you mean a rubber hose? There is a vacuum tree near the rear of the engine where several hoses connect. See if it has come loose from that. If so you have a vacuum leak and that would explain the rough running.

the van won't start. When you turn the key is just goes click. the lights work fine. all the dash lights come on. I tried boosting but with the same results

Vacuume leak? Look for a loose hose.