740GLE wont run properly over 2000revs

i have just purchased a 1986 Dreg 740GLE, 138k. Seems to run ok until i try to accelerate.....rev needle jumps all over the place.up down up,instant loss of power then surges back again. Cant seem to get it to run smooth over 2000 revs. Chap i bought off had just changed plugs leads distributer cap and rotor arm. Will need someone to look at it as not confident at DIY but would like some idea of what to be looking at.
Help needed please.

Paul J

ps anyone know of a volvo mechanic/Leicestershire ? (not main dealers)

[Peter Milnes]

Check for disturbed connectors especially the one feeding the ignition power amplifier which is between the air filter box and the inner wing. They suffer from a poor earth connection and connector, plus poor heatsink contact with it's metal mounting plate.

Keep us up to date with your findings, please.

All the best, Peter.

[Suterman]

Also could be worth checking the main engine earth strap(s) pictured below, Make sure its not freyed and that at each end the strap and anchor point is clean(good contact) and tightly bolted down

thank you both for advice, have been driving it gingerly today but seems to be getting worse, rev needle will drop like a stone and loss of power every now and then... at any revs now, then will come back.
Have day off tomorrow so am going to check the things you have said.

Paul J

OK, the story so far. engine type B230E, have taken advice...changed earth strap as old 1 appeared worn and frayed.....undid ignition amplifier from inner wing...checked contacts and re connected. The car did seem to run better but problem still there.......can be driving along fine....then sudden flick of rev counter, car lurches forward as though no power....then back on again.

Interesting thing....the idle speed seemed to be too fast after id done the above..(1100), so lowered it, but after the fault occurs...whilst sittin at lights it seems to be idling fast again.

anybody got any ideas?

Paul J