94 thunderbird question

I have a 94 thunderbird, 180,000 miles on it. it surges back and forth at all speeds although, I did put it in second gear and brought it up past 3500 rpm and it seemed to run fine. I also noticed that my oil pressure
keeps dropping to low then goes back to normal. I know that my valve seals are leaking cuz I get a puff of smoke when I start the car but, that shouldn't make the car run bad. I just changed the oil put new plugs, cap and rotor in. timing is good. I put a new fuel filter in and a pcv valve. I had a vacuum leak, fixed that. i checked the codes and I only get a code for the hego sensor but that has been like that for about 4 years now. the car always ran great. I would appreciate any help. thank you
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j wrote:

Maybe IAC valve or TPS, maybe clogged cat. The oil pressure sounds like a clogged pickup if the change doesn't correspond to RPM. Put a mechanical gauge on the oil port to see what actual pressures are at various RPM (with engine warmed up).
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j <none> wrote:

Well, I supect that code for the EGO sensor might reflect that it's fouled up.
Your oil sender is a 'fooler' switch, if it's wavering that is not a good sign unless it's an electrical problem which it may be. And which might reflect on the 'surging' at any speed.
When i've had that it was related to a bad ground on the computer harness.
Or it could maybe be the block to firewall ground strap.
OR you might have been using a very famous oil and the engine, including pikups or returns, is all sludged up. too many possibilities, sadly.
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