Seeking some help on my 89 f150 5.0(2wd)
can't seem to pull codes to save my life.
I've replaced map sensor,tps,ecu,icm and both coolant sensors.
Ive.gone through the forum and worked with what I found but still having a few issues that I believe are electrical.

1. While driving sometimes it sounds like a dial is just consistently running loudly but the Odometer seems to be working fine

2. SOMETIMES when going to drive or reverse from park rpm drop really low then bounces back.(replaced map due to rough idle, fixed idle issue but this issue still exists even tested iac and fuel reg.)

3. when getting on interstate trying to get up to speed engine light flashes but only under full acceleration.

4. Replaced both coolent sensors under hood but guage won't go over the first line. It will move a total of 1/8" maybe but that's it.

any help is appreciated

 

When you say you can't pull codes, do you mean you follow the procedure for pulling codes and the check engine light or code reader doesn't work?
A "dial consistently running" sounds like your speedometer cable is rattling.
I don't have experience with automatic transmissions, so I can't help with question 2.
The check engine light flashing on issue is best investigated by figuring out how to pull engine codes.
Sounds like your thermostat might be faulty. I would buy a reasonably priced infrared temperature gun and investigate how warm the engine and coolant lines are getting.
I replaced all my vacuum lines, except the one to the MAP sensor, with 5/32" rubber hose. How are yours? At this age, the factory vacuum lines are brittle if not cracked.

 

Replace your thermostat and make sure it is a 192-195 degree
I believe Soup Bean is right and you need to pull that speedo cable and lube it.
Pull it down and away from the cluster, remove the cable, squirt a bunch of spray grease in the housing and reinstall the cable
If your cable has worn into the housing the noise will still be there
Lube it twice or three times like that, removing the cable each time
Question 2 sounds about normal for an older truck without EEC5 (responds quicker)
Do not drive it much with the check engine lamp flashing
It may be trying to flash out a code? for you
During the self test on an old EEC4, when you perform the BOO test and smack the motor for the knock sensor
Combined with the brief WOT, that is when the codes get outputted
Slim chance yours is being fooled into code output when you accelerate hard?

 

Along with the above advice, also check the vacuum canister integrity. Those soup cans do rust out.
We just replaced one on an 89 F350 with a home made pvc pipe and caps.