I have a 1990 Ford F250 7.5L v8 2WD. A few weeks ago I added oil(the correct kind) and the truck began to have a ticking sound from under the truck. And when I’m slowly accelerating at 35mph to 45mph there is a shudder from the entire truck. Also when I hit 70mph the truck runs terribly. I thought it was the U-Joints so I replaced those but they where not the cause. I individually pulled the spark plug wires off the distributor as the truck was idling and the tick was constant. The truck has plenty of transmission fluid(right color right smell) and is shifting properly. It is however running rich and it does not have the usual deep rumble when accelerating. The truck has 168000 miles.
RESPONSE
Ticking Sound
Sometimes a ticking sound can be from different things. It can be internal in the engine caused from lack of lubrication or worn parts. It can be external from a bearing on a tensioner or pulley. And can sometimes be from an electrical short from a plug or plug wire. Sometimes it can even be inside the distributor cap.
Since your truck is also running rough and rich the ticking sound may be relevant.
First of all if the check engine light is on or not check for any stored codes and post them below. The codes can be checked without a scan tool.
No Codes Found
Furthermore if no engine trouble codes are found you can move on to eliminating a few things. Remove the drive belt/s and start the engine for a short period. Listen to see if the ticking sound has gone since the drive pulleys are not being turned. If the noise is gone, spin the pulleys by hand and replace the faulty part. Noise still there? Put the belt back on. Remove the spark plugs and examine each one carefully. Look for one or ones that are fouled. This will indicate a cylinder that is not firing properly. Examine the spark plug wires for those plugs for any cracks or burn marks. If the wires lay against the block they can burn and cause an arch that can be heard as a ticking sound. Also if a spark plug has a crack in it the same may occur.
Night Test
Sometimes it is easier to look for an electrical arch when it is dark outside. Simply start the engine and pop the hood. Look any yellow or blue spark around the spark plug area and plug wires.
If it has been a while since you have tuned up your rig it may be a good idea to go ahead and replace the spark plugs, wires cap and rotor.