Ok here we go i have a 91 bonneville se i love her dearly but have a miss in the engine and cant find it, i have already replaced plugs,wires,coil pack it has the magnavox set all in one,ignition module, fuel filter and finally the computer, i have also checked my fuel pressure its running 35 psi @ idle and 40 @ throttle up, it starts out smooth but after about 15 to 20 miles it starts missing, but isnt constant sometimes it smoothes out like it never happened, so i dont think its a valve or broken ring ,so any good ideas out there i know that you guys have had several post like this but none have went as far as ive seen or noticed. any help would be nice thanks guys in advance

First thought is a fouled injector or sticking valve when hot. Try a bottle of quality fuel injector cleaner.
You can also do a compression check on all cylinders to see if there are any issues in one particular cylinder.
Also the throttle body should be cleaned and the sensors removed for cleaning.
The TPS voltage at idle should also be checked.

i replaced both the icm and coil pack and i intend to go back to the mechanic tuesday and do a compression check, as soon as i can im going to try cleaning the tps, i already cleaned the screen on the throttle body, i appreciate the replies so much keep the ideas coming

we took it to our mechanic today and he put it back on the computer and he found the crank sensor was going bad, replaced it now it seems to be fine,thanks for all the help guys.

Check if the injectors has a short when this happening. If not
In my opinion, if you have already changed the coilpack and still having "scattered misses" without gas smell or backfires, I would check the fuel filter first and the gas tank condition for any glogging.
I hope your gas tank was never weld repaired otherwise this might be the cause where the internal corrosion along the years would produce so many alien particles that they will eventually contaminate the fuel and clog the jets and causing your misses.
A good test would be to feed the car from a portable gas tank and let run to see if you can reproduce the same symptom first. If the symptom repeats then you may eliminate the gas tank and fuel filter and gas line and then check the fuel pump for possible excessive particle trapped.
I hope this can help resolve your issue.

as a contributor and concentrate your querie